// jpgd.cpp - C++ class for JPEG decompression.
// Public domain, Rich Geldreich <richgel99@gmail.com>
// Alex Evans: Linear memory allocator (taken from jpge.h).
// v1.04, May. 19, 2012: Code tweaks to fix VS2008 static code analysis warnings (all looked harmless)
//
// Supports progressive and baseline sequential JPEG image files, and the most common chroma subsampling factors: Y, H1V1, H2V1, H1V2, and H2V2.
//
// Chroma upsampling quality: H2V2 is upsampled in the frequency domain, H2V1 and H1V2 are upsampled using point sampling.
// Chroma upsampling reference: "Fast Scheme for Image Size Change in the Compressed Domain"
// http://vision.ai.uiuc.edu/~dugad/research/dct/index.html

#include "jpgd.h"
#include <string.h>

#include <assert.h>
#define JPGD_ASSERT(x) assert(x)

#ifdef _MSC_VER
#pragma warning (disable : 4611) // warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable
#endif

// Set to 1 to enable freq. domain chroma upsampling on images using H2V2 subsampling (0=faster nearest neighbor sampling).
// This is slower, but results in higher quality on images with highly saturated colors.
#define JPGD_SUPPORT_FREQ_DOMAIN_UPSAMPLING 1

#define JPGD_TRUE (1)
#define JPGD_FALSE (0)

#define JPGD_MAX(a,b) (((a)>(b)) ? (a) : (b))
#define JPGD_MIN(a,b) (((a)<(b)) ? (a) : (b))

namespace jpgd
{

static inline void *jpgd_malloc(size_t nSize)
{
	return malloc(nSize);
}
static inline void jpgd_free(void *p)
{
	free(p);
}

// DCT coefficients are stored in this sequence.
static int g_ZAG[64] = {  0,1,8,16,9,2,3,10,17,24,32,25,18,11,4,5,12,19,26,33,40,48,41,34,27,20,13,6,7,14,21,28,35,42,49,56,57,50,43,36,29,22,15,23,30,37,44,51,58,59,52,45,38,31,39,46,53,60,61,54,47,55,62,63 };

enum JPEG_MARKER {
	M_SOF0  = 0xC0, M_SOF1  = 0xC1, M_SOF2  = 0xC2, M_SOF3  = 0xC3, M_SOF5  = 0xC5, M_SOF6  = 0xC6, M_SOF7  = 0xC7, M_JPG   = 0xC8,
	M_SOF9  = 0xC9, M_SOF10 = 0xCA, M_SOF11 = 0xCB, M_SOF13 = 0xCD, M_SOF14 = 0xCE, M_SOF15 = 0xCF, M_DHT   = 0xC4, M_DAC   = 0xCC,
	M_RST0  = 0xD0, M_RST1  = 0xD1, M_RST2  = 0xD2, M_RST3  = 0xD3, M_RST4  = 0xD4, M_RST5  = 0xD5, M_RST6  = 0xD6, M_RST7  = 0xD7,
	M_SOI   = 0xD8, M_EOI   = 0xD9, M_SOS   = 0xDA, M_DQT   = 0xDB, M_DNL   = 0xDC, M_DRI   = 0xDD, M_DHP   = 0xDE, M_EXP   = 0xDF,
	M_APP0  = 0xE0, M_APP15 = 0xEF, M_JPG0  = 0xF0, M_JPG13 = 0xFD, M_COM   = 0xFE, M_TEM   = 0x01, M_ERROR = 0x100, RST0   = 0xD0
};

enum JPEG_SUBSAMPLING { JPGD_GRAYSCALE = 0, JPGD_YH1V1, JPGD_YH2V1, JPGD_YH1V2, JPGD_YH2V2 };

#define CONST_BITS  13
#define PASS1_BITS  2
#define SCALEDONE ((int32)1)

#define FIX_0_298631336  ((int32)2446)        /* FIX(0.298631336) */
#define FIX_0_390180644  ((int32)3196)        /* FIX(0.390180644) */
#define FIX_0_541196100  ((int32)4433)        /* FIX(0.541196100) */
#define FIX_0_765366865  ((int32)6270)        /* FIX(0.765366865) */
#define FIX_0_899976223  ((int32)7373)        /* FIX(0.899976223) */
#define FIX_1_175875602  ((int32)9633)        /* FIX(1.175875602) */
#define FIX_1_501321110  ((int32)12299)       /* FIX(1.501321110) */
#define FIX_1_847759065  ((int32)15137)       /* FIX(1.847759065) */
#define FIX_1_961570560  ((int32)16069)       /* FIX(1.961570560) */
#define FIX_2_053119869  ((int32)16819)       /* FIX(2.053119869) */
#define FIX_2_562915447  ((int32)20995)       /* FIX(2.562915447) */
#define FIX_3_072711026  ((int32)25172)       /* FIX(3.072711026) */

#define DESCALE(x,n)  (((x) + (SCALEDONE << ((n)-1))) >> (n))
#define DESCALE_ZEROSHIFT(x,n)  (((x) + (128 << (n)) + (SCALEDONE << ((n)-1))) >> (n))

#define MULTIPLY(var, cnst)  ((var) * (cnst))

#define CLAMP(i) ((static_cast<uint>(i) > 255) ? (((~i) >> 31) & 0xFF) : (i))

// Compiler creates a fast path 1D IDCT for X non-zero columns
template <int NONZERO_COLS>
struct Row {
	static void idct(int* pTemp, const jpgd_block_t* pSrc) {
		// ACCESS_COL() will be optimized at compile time to either an array access, or 0.
#define ACCESS_COL(x) (((x) < NONZERO_COLS) ? (int)pSrc[x] : 0)

		const int z2 = ACCESS_COL(2), z3 = ACCESS_COL(6);

		const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
		const int tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
		const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);

		const int tmp0 = (ACCESS_COL(0) + ACCESS_COL(4)) << CONST_BITS;
		const int tmp1 = (ACCESS_COL(0) - ACCESS_COL(4)) << CONST_BITS;

		const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;

		const int atmp0 = ACCESS_COL(7), atmp1 = ACCESS_COL(5), atmp2 = ACCESS_COL(3), atmp3 = ACCESS_COL(1);

		const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
		const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);

		const int az1 = MULTIPLY(bz1, - FIX_0_899976223);
		const int az2 = MULTIPLY(bz2, - FIX_2_562915447);
		const int az3 = MULTIPLY(bz3, - FIX_1_961570560) + bz5;
		const int az4 = MULTIPLY(bz4, - FIX_0_390180644) + bz5;

		const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
		const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
		const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
		const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;

		pTemp[0] = DESCALE(tmp10 + btmp3, CONST_BITS-PASS1_BITS);
		pTemp[7] = DESCALE(tmp10 - btmp3, CONST_BITS-PASS1_BITS);
		pTemp[1] = DESCALE(tmp11 + btmp2, CONST_BITS-PASS1_BITS);
		pTemp[6] = DESCALE(tmp11 - btmp2, CONST_BITS-PASS1_BITS);
		pTemp[2] = DESCALE(tmp12 + btmp1, CONST_BITS-PASS1_BITS);
		pTemp[5] = DESCALE(tmp12 - btmp1, CONST_BITS-PASS1_BITS);
		pTemp[3] = DESCALE(tmp13 + btmp0, CONST_BITS-PASS1_BITS);
		pTemp[4] = DESCALE(tmp13 - btmp0, CONST_BITS-PASS1_BITS);
	}
};

template <>
struct Row<0> {
	static void idct(int* pTemp, const jpgd_block_t* pSrc) {
#ifdef _MSC_VER
		pTemp;
		pSrc;
#endif
	}
};

template <>
struct Row<1> {
	static void idct(int* pTemp, const jpgd_block_t* pSrc) {
		const int dcval = (pSrc[0] << PASS1_BITS);

		pTemp[0] = dcval;
		pTemp[1] = dcval;
		pTemp[2] = dcval;
		pTemp[3] = dcval;
		pTemp[4] = dcval;
		pTemp[5] = dcval;
		pTemp[6] = dcval;
		pTemp[7] = dcval;
	}
};

// Compiler creates a fast path 1D IDCT for X non-zero rows
template <int NONZERO_ROWS>
struct Col {
	static void idct(uint8* pDst_ptr, const int* pTemp) {
		// ACCESS_ROW() will be optimized at compile time to either an array access, or 0.
#define ACCESS_ROW(x) (((x) < NONZERO_ROWS) ? pTemp[x * 8] : 0)

		const int z2 = ACCESS_ROW(2);
		const int z3 = ACCESS_ROW(6);

		const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
		const int tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
		const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);

		const int tmp0 = (ACCESS_ROW(0) + ACCESS_ROW(4)) << CONST_BITS;
		const int tmp1 = (ACCESS_ROW(0) - ACCESS_ROW(4)) << CONST_BITS;

		const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;

		const int atmp0 = ACCESS_ROW(7), atmp1 = ACCESS_ROW(5), atmp2 = ACCESS_ROW(3), atmp3 = ACCESS_ROW(1);

		const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
		const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);

		const int az1 = MULTIPLY(bz1, - FIX_0_899976223);
		const int az2 = MULTIPLY(bz2, - FIX_2_562915447);
		const int az3 = MULTIPLY(bz3, - FIX_1_961570560) + bz5;
		const int az4 = MULTIPLY(bz4, - FIX_0_390180644) + bz5;

		const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
		const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
		const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
		const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;

		int i = DESCALE_ZEROSHIFT(tmp10 + btmp3, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*0] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp10 - btmp3, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*7] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp11 + btmp2, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*1] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp11 - btmp2, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*6] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp12 + btmp1, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*2] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp12 - btmp1, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*5] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp13 + btmp0, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*3] = (uint8)CLAMP(i);

		i = DESCALE_ZEROSHIFT(tmp13 - btmp0, CONST_BITS+PASS1_BITS+3);
		pDst_ptr[8*4] = (uint8)CLAMP(i);
	}
};

template <>
struct Col<1> {
	static void idct(uint8* pDst_ptr, const int* pTemp) {
		int dcval = DESCALE_ZEROSHIFT(pTemp[0], PASS1_BITS+3);
		const uint8 dcval_clamped = (uint8)CLAMP(dcval);
		pDst_ptr[0*8] = dcval_clamped;
		pDst_ptr[1*8] = dcval_clamped;
		pDst_ptr[2*8] = dcval_clamped;
		pDst_ptr[3*8] = dcval_clamped;
		pDst_ptr[4*8] = dcval_clamped;
		pDst_ptr[5*8] = dcval_clamped;
		pDst_ptr[6*8] = dcval_clamped;
		pDst_ptr[7*8] = dcval_clamped;
	}
};

static const uint8 s_idct_row_table[] = {
	1,0,0,0,0,0,0,0, 2,0,0,0,0,0,0,0, 2,1,0,0,0,0,0,0, 2,1,1,0,0,0,0,0, 2,2,1,0,0,0,0,0, 3,2,1,0,0,0,0,0, 4,2,1,0,0,0,0,0, 4,3,1,0,0,0,0,0,
	4,3,2,0,0,0,0,0, 4,3,2,1,0,0,0,0, 4,3,2,1,1,0,0,0, 4,3,2,2,1,0,0,0, 4,3,3,2,1,0,0,0, 4,4,3,2,1,0,0,0, 5,4,3,2,1,0,0,0, 6,4,3,2,1,0,0,0,
	6,5,3,2,1,0,0,0, 6,5,4,2,1,0,0,0, 6,5,4,3,1,0,0,0, 6,5,4,3,2,0,0,0, 6,5,4,3,2,1,0,0, 6,5,4,3,2,1,1,0, 6,5,4,3,2,2,1,0, 6,5,4,3,3,2,1,0,
	6,5,4,4,3,2,1,0, 6,5,5,4,3,2,1,0, 6,6,5,4,3,2,1,0, 7,6,5,4,3,2,1,0, 8,6,5,4,3,2,1,0, 8,7,5,4,3,2,1,0, 8,7,6,4,3,2,1,0, 8,7,6,5,3,2,1,0,
	8,7,6,5,4,2,1,0, 8,7,6,5,4,3,1,0, 8,7,6,5,4,3,2,0, 8,7,6,5,4,3,2,1, 8,7,6,5,4,3,2,2, 8,7,6,5,4,3,3,2, 8,7,6,5,4,4,3,2, 8,7,6,5,5,4,3,2,
	8,7,6,6,5,4,3,2, 8,7,7,6,5,4,3,2, 8,8,7,6,5,4,3,2, 8,8,8,6,5,4,3,2, 8,8,8,7,5,4,3,2, 8,8,8,7,6,4,3,2, 8,8,8,7,6,5,3,2, 8,8,8,7,6,5,4,2,
	8,8,8,7,6,5,4,3, 8,8,8,7,6,5,4,4, 8,8,8,7,6,5,5,4, 8,8,8,7,6,6,5,4, 8,8,8,7,7,6,5,4, 8,8,8,8,7,6,5,4, 8,8,8,8,8,6,5,4, 8,8,8,8,8,7,5,4,
	8,8,8,8,8,7,6,4, 8,8,8,8,8,7,6,5, 8,8,8,8,8,7,6,6, 8,8,8,8,8,7,7,6, 8,8,8,8,8,8,7,6, 8,8,8,8,8,8,8,6, 8,8,8,8,8,8,8,7, 8,8,8,8,8,8,8,8,
};

static const uint8 s_idct_col_table[] = { 1, 1, 2, 3, 3, 3, 3, 3, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 };

void idct(const jpgd_block_t* pSrc_ptr, uint8* pDst_ptr, int block_max_zag)
{
	JPGD_ASSERT(block_max_zag >= 1);
	JPGD_ASSERT(block_max_zag <= 64);

	if (block_max_zag <= 1) {
		int k = ((pSrc_ptr[0] + 4) >> 3) + 128;
		k = CLAMP(k);
		k = k | (k<<8);
		k = k | (k<<16);

		for (int i = 8; i > 0; i--) {
			*(int*)&pDst_ptr[0] = k;
			*(int*)&pDst_ptr[4] = k;
			pDst_ptr += 8;
		}
		return;
	}

	int temp[64];

	const jpgd_block_t* pSrc = pSrc_ptr;
	int* pTemp = temp;

	const uint8* pRow_tab = &s_idct_row_table[(block_max_zag - 1) * 8];
	int i;
	for (i = 8; i > 0; i--, pRow_tab++) {
		switch (*pRow_tab) {
		case 0:
			Row<0>::idct(pTemp, pSrc);
			break;
		case 1:
			Row<1>::idct(pTemp, pSrc);
			break;
		case 2:
			Row<2>::idct(pTemp, pSrc);
			break;
		case 3:
			Row<3>::idct(pTemp, pSrc);
			break;
		case 4:
			Row<4>::idct(pTemp, pSrc);
			break;
		case 5:
			Row<5>::idct(pTemp, pSrc);
			break;
		case 6:
			Row<6>::idct(pTemp, pSrc);
			break;
		case 7:
			Row<7>::idct(pTemp, pSrc);
			break;
		case 8:
			Row<8>::idct(pTemp, pSrc);
			break;
		}

		pSrc += 8;
		pTemp += 8;
	}

	pTemp = temp;

	const int nonzero_rows = s_idct_col_table[block_max_zag - 1];
	for (i = 8; i > 0; i--) {
		switch (nonzero_rows) {
		case 1:
			Col<1>::idct(pDst_ptr, pTemp);
			break;
		case 2:
			Col<2>::idct(pDst_ptr, pTemp);
			break;
		case 3:
			Col<3>::idct(pDst_ptr, pTemp);
			break;
		case 4:
			Col<4>::idct(pDst_ptr, pTemp);
			break;
		case 5:
			Col<5>::idct(pDst_ptr, pTemp);
			break;
		case 6:
			Col<6>::idct(pDst_ptr, pTemp);
			break;
		case 7:
			Col<7>::idct(pDst_ptr, pTemp);
			break;
		case 8:
			Col<8>::idct(pDst_ptr, pTemp);
			break;
		}

		pTemp++;
		pDst_ptr++;
	}
}

void idct_4x4(const jpgd_block_t* pSrc_ptr, uint8* pDst_ptr)
{
	int i;
	int temp[64];
	int* pTemp = temp;
	const jpgd_block_t* pSrc = pSrc_ptr;

	for (i = 4; i > 0; i--) {
		Row<4>::idct(pTemp, pSrc);
		pSrc += 8;
		pTemp += 8;
	}

	pTemp = temp;
	for (i = 8; i > 0; i--) {
		Col<4>::idct(pDst_ptr, pTemp);
		pTemp++;
		pDst_ptr++;
	}
}

// Retrieve one character from the input stream.
inline uint jpeg_decoder::get_char()
{
	// Any bytes remaining in buffer?
	if (!m_in_buf_left) {
		// Try to get more bytes.
		prep_in_buffer();
		// Still nothing to get?
		if (!m_in_buf_left) {
			// Pad the end of the stream with 0xFF 0xD9 (EOI marker)
			int t = m_tem_flag;
			m_tem_flag ^= 1;
			if (t)
				return 0xD9;
			else
				return 0xFF;
		}
	}

	uint c = *m_pIn_buf_ofs++;
	m_in_buf_left--;

	return c;
}

// Same as previous method, except can indicate if the character is a pad character or not.
inline uint jpeg_decoder::get_char(bool *pPadding_flag)
{
	if (!m_in_buf_left) {
		prep_in_buffer();
		if (!m_in_buf_left) {
			*pPadding_flag = true;
			int t = m_tem_flag;
			m_tem_flag ^= 1;
			if (t)
				return 0xD9;
			else
				return 0xFF;
		}
	}

	*pPadding_flag = false;

	uint c = *m_pIn_buf_ofs++;
	m_in_buf_left--;

	return c;
}

// Inserts a previously retrieved character back into the input buffer.
inline void jpeg_decoder::stuff_char(uint8 q)
{
	*(--m_pIn_buf_ofs) = q;
	m_in_buf_left++;
}

// Retrieves one character from the input stream, but does not read past markers. Will continue to return 0xFF when a marker is encountered.
inline uint8 jpeg_decoder::get_octet()
{
	bool padding_flag;
	int c = get_char(&padding_flag);

	if (c == 0xFF) {
		if (padding_flag)
			return 0xFF;

		c = get_char(&padding_flag);
		if (padding_flag) {
			stuff_char(0xFF);
			return 0xFF;
		}

		if (c == 0x00)
			return 0xFF;
		else {
			stuff_char(static_cast<uint8>(c));
			stuff_char(0xFF);
			return 0xFF;
		}
	}

	return static_cast<uint8>(c);
}

// Retrieves a variable number of bits from the input stream. Does not recognize markers.
inline uint jpeg_decoder::get_bits(int num_bits)
{
	if (!num_bits)
		return 0;

	uint i = m_bit_buf >> (32 - num_bits);

	if ((m_bits_left -= num_bits) <= 0) {
		m_bit_buf <<= (num_bits += m_bits_left);

		uint c1 = get_char();
		uint c2 = get_char();
		m_bit_buf = (m_bit_buf & 0xFFFF0000) | (c1 << 8) | c2;

		m_bit_buf <<= -m_bits_left;

		m_bits_left += 16;

		JPGD_ASSERT(m_bits_left >= 0);
	} else
		m_bit_buf <<= num_bits;

	return i;
}

// Retrieves a variable number of bits from the input stream. Markers will not be read into the input bit buffer. Instead, an infinite number of all 1's will be returned when a marker is encountered.
inline uint jpeg_decoder::get_bits_no_markers(int num_bits)
{
	if (!num_bits)
		return 0;

	uint i = m_bit_buf >> (32 - num_bits);

	if ((m_bits_left -= num_bits) <= 0) {
		m_bit_buf <<= (num_bits += m_bits_left);

		if ((m_in_buf_left < 2) || (m_pIn_buf_ofs[0] == 0xFF) || (m_pIn_buf_ofs[1] == 0xFF)) {
			uint c1 = get_octet();
			uint c2 = get_octet();
			m_bit_buf |= (c1 << 8) | c2;
		} else {
			m_bit_buf |= ((uint)m_pIn_buf_ofs[0] << 8) | m_pIn_buf_ofs[1];
			m_in_buf_left -= 2;
			m_pIn_buf_ofs += 2;
		}

		m_bit_buf <<= -m_bits_left;

		m_bits_left += 16;

		JPGD_ASSERT(m_bits_left >= 0);
	} else
		m_bit_buf <<= num_bits;

	return i;
}

// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables *pH)
{
	int symbol;

	// Check first 8-bits: do we have a complete symbol?
	if ((symbol = pH->look_up[m_bit_buf >> 24]) < 0) {
		// Decode more bits, use a tree traversal to find symbol.
		int ofs = 23;
		do {
			symbol = pH->tree[-(int)(symbol + ((m_bit_buf >> ofs) & 1))];
			ofs--;
		} while (symbol < 0);

		get_bits_no_markers(8 + (23 - ofs));
	} else
		get_bits_no_markers(pH->code_size[symbol]);

	return symbol;
}

// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables *pH, int& extra_bits)
{
	int symbol;

	// Check first 8-bits: do we have a complete symbol?
	if ((symbol = pH->look_up2[m_bit_buf >> 24]) < 0) {
		// Use a tree traversal to find symbol.
		int ofs = 23;
		do {
			symbol = pH->tree[-(int)(symbol + ((m_bit_buf >> ofs) & 1))];
			ofs--;
		} while (symbol < 0);

		get_bits_no_markers(8 + (23 - ofs));

		extra_bits = get_bits_no_markers(symbol & 0xF);
	} else {
		JPGD_ASSERT(((symbol >> 8) & 31) == pH->code_size[symbol & 255] + ((symbol & 0x8000) ? (symbol & 15) : 0));

		if (symbol & 0x8000) {
			get_bits_no_markers((symbol >> 8) & 31);
			extra_bits = symbol >> 16;
		} else {
			int code_size = (symbol >> 8) & 31;
			int num_extra_bits = symbol & 0xF;
			int bits = code_size + num_extra_bits;
			if (bits <= (m_bits_left + 16))
				extra_bits = get_bits_no_markers(bits) & ((1 << num_extra_bits) - 1);
			else {
				get_bits_no_markers(code_size);
				extra_bits = get_bits_no_markers(num_extra_bits);
			}
		}

		symbol &= 0xFF;
	}

	return symbol;
}

// Tables and macro used to fully decode the DPCM differences.
static const int s_extend_test[16] = { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
static const int s_extend_offset[16] = { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
static const int s_extend_mask[] = { 0, (1<<0), (1<<1), (1<<2), (1<<3), (1<<4), (1<<5), (1<<6), (1<<7), (1<<8), (1<<9), (1<<10), (1<<11), (1<<12), (1<<13), (1<<14), (1<<15), (1<<16) };
// The logical AND's in this macro are to shut up static code analysis (aren't really necessary - couldn't find another way to do this)
#define JPGD_HUFF_EXTEND(x, s) (((x) < s_extend_test[s & 15]) ? ((x) + s_extend_offset[s & 15]) : (x))

// Clamps a value between 0-255.
inline uint8 jpeg_decoder::clamp(int i)
{
	if (static_cast<uint>(i) > 255)
		i = (((~i) >> 31) & 0xFF);

	return static_cast<uint8>(i);
}

namespace DCT_Upsample
{
struct Matrix44 {
	typedef int Element_Type;
	enum { NUM_ROWS = 4, NUM_COLS = 4 };

	Element_Type v[NUM_ROWS][NUM_COLS];

	inline int rows() const {
		return NUM_ROWS;
	}
	inline int cols() const {
		return NUM_COLS;
	}

	inline const Element_Type & at(int r, int c) const {
		return v[r][c];
	}
	inline       Element_Type & at(int r, int c)       {
		return v[r][c];
	}

	inline Matrix44() { }

	inline Matrix44& operator += (const Matrix44& a) {
		for (int r = 0; r < NUM_ROWS; r++) {
			at(r, 0) += a.at(r, 0);
			at(r, 1) += a.at(r, 1);
			at(r, 2) += a.at(r, 2);
			at(r, 3) += a.at(r, 3);
		}
		return *this;
	}

	inline Matrix44& operator -= (const Matrix44& a) {
		for (int r = 0; r < NUM_ROWS; r++) {
			at(r, 0) -= a.at(r, 0);
			at(r, 1) -= a.at(r, 1);
			at(r, 2) -= a.at(r, 2);
			at(r, 3) -= a.at(r, 3);
		}
		return *this;
	}

	friend inline Matrix44 operator + (const Matrix44& a, const Matrix44& b) {
		Matrix44 ret;
		for (int r = 0; r < NUM_ROWS; r++) {
			ret.at(r, 0) = a.at(r, 0) + b.at(r, 0);
			ret.at(r, 1) = a.at(r, 1) + b.at(r, 1);
			ret.at(r, 2) = a.at(r, 2) + b.at(r, 2);
			ret.at(r, 3) = a.at(r, 3) + b.at(r, 3);
		}
		return ret;
	}

	friend inline Matrix44 operator - (const Matrix44& a, const Matrix44& b) {
		Matrix44 ret;
		for (int r = 0; r < NUM_ROWS; r++) {
			ret.at(r, 0) = a.at(r, 0) - b.at(r, 0);
			ret.at(r, 1) = a.at(r, 1) - b.at(r, 1);
			ret.at(r, 2) = a.at(r, 2) - b.at(r, 2);
			ret.at(r, 3) = a.at(r, 3) - b.at(r, 3);
		}
		return ret;
	}

	static inline void add_and_store(jpgd_block_t* pDst, const Matrix44& a, const Matrix44& b) {
		for (int r = 0; r < 4; r++) {
			pDst[0*8 + r] = static_cast<jpgd_block_t>(a.at(r, 0) + b.at(r, 0));
			pDst[1*8 + r] = static_cast<jpgd_block_t>(a.at(r, 1) + b.at(r, 1));
			pDst[2*8 + r] = static_cast<jpgd_block_t>(a.at(r, 2) + b.at(r, 2));
			pDst[3*8 + r] = static_cast<jpgd_block_t>(a.at(r, 3) + b.at(r, 3));
		}
	}

	static inline void sub_and_store(jpgd_block_t* pDst, const Matrix44& a, const Matrix44& b) {
		for (int r = 0; r < 4; r++) {
			pDst[0*8 + r] = static_cast<jpgd_block_t>(a.at(r, 0) - b.at(r, 0));
			pDst[1*8 + r] = static_cast<jpgd_block_t>(a.at(r, 1) - b.at(r, 1));
			pDst[2*8 + r] = static_cast<jpgd_block_t>(a.at(r, 2) - b.at(r, 2));
			pDst[3*8 + r] = static_cast<jpgd_block_t>(a.at(r, 3) - b.at(r, 3));
		}
	}
};

const int FRACT_BITS = 10;
const int SCALE = 1 << FRACT_BITS;

typedef int Temp_Type;
#define D(i) (((i) + (SCALE >> 1)) >> FRACT_BITS)
#define F(i) ((int)((i) * SCALE + .5f))

// Any decent C++ compiler will optimize this at compile time to a 0, or an array access.
#define AT(c, r) ((((c)>=NUM_COLS)||((r)>=NUM_ROWS)) ? 0 : pSrc[(c)+(r)*8])

// NUM_ROWS/NUM_COLS = # of non-zero rows/cols in input matrix
template<int NUM_ROWS, int NUM_COLS>
struct P_Q {
	static void calc(Matrix44& P, Matrix44& Q, const jpgd_block_t* pSrc) {
		// 4x8 = 4x8 times 8x8, matrix 0 is constant
		const Temp_Type X000 = AT(0, 0);
		const Temp_Type X001 = AT(0, 1);
		const Temp_Type X002 = AT(0, 2);
		const Temp_Type X003 = AT(0, 3);
		const Temp_Type X004 = AT(0, 4);
		const Temp_Type X005 = AT(0, 5);
		const Temp_Type X006 = AT(0, 6);
		const Temp_Type X007 = AT(0, 7);
		const Temp_Type X010 = D(F(0.415735f) * AT(1, 0) + F(0.791065f) * AT(3, 0) + F(-0.352443f) * AT(5, 0) + F(0.277785f) * AT(7, 0));
		const Temp_Type X011 = D(F(0.415735f) * AT(1, 1) + F(0.791065f) * AT(3, 1) + F(-0.352443f) * AT(5, 1) + F(0.277785f) * AT(7, 1));
		const Temp_Type X012 = D(F(0.415735f) * AT(1, 2) + F(0.791065f) * AT(3, 2) + F(-0.352443f) * AT(5, 2) + F(0.277785f) * AT(7, 2));
		const Temp_Type X013 = D(F(0.415735f) * AT(1, 3) + F(0.791065f) * AT(3, 3) + F(-0.352443f) * AT(5, 3) + F(0.277785f) * AT(7, 3));
		const Temp_Type X014 = D(F(0.415735f) * AT(1, 4) + F(0.791065f) * AT(3, 4) + F(-0.352443f) * AT(5, 4) + F(0.277785f) * AT(7, 4));
		const Temp_Type X015 = D(F(0.415735f) * AT(1, 5) + F(0.791065f) * AT(3, 5) + F(-0.352443f) * AT(5, 5) + F(0.277785f) * AT(7, 5));
		const Temp_Type X016 = D(F(0.415735f) * AT(1, 6) + F(0.791065f) * AT(3, 6) + F(-0.352443f) * AT(5, 6) + F(0.277785f) * AT(7, 6));
		const Temp_Type X017 = D(F(0.415735f) * AT(1, 7) + F(0.791065f) * AT(3, 7) + F(-0.352443f) * AT(5, 7) + F(0.277785f) * AT(7, 7));
		const Temp_Type X020 = AT(4, 0);
		const Temp_Type X021 = AT(4, 1);
		const Temp_Type X022 = AT(4, 2);
		const Temp_Type X023 = AT(4, 3);
		const Temp_Type X024 = AT(4, 4);
		const Temp_Type X025 = AT(4, 5);
		const Temp_Type X026 = AT(4, 6);
		const Temp_Type X027 = AT(4, 7);
		const Temp_Type X030 = D(F(0.022887f) * AT(1, 0) + F(-0.097545f) * AT(3, 0) + F(0.490393f) * AT(5, 0) + F(0.865723f) * AT(7, 0));
		const Temp_Type X031 = D(F(0.022887f) * AT(1, 1) + F(-0.097545f) * AT(3, 1) + F(0.490393f) * AT(5, 1) + F(0.865723f) * AT(7, 1));
		const Temp_Type X032 = D(F(0.022887f) * AT(1, 2) + F(-0.097545f) * AT(3, 2) + F(0.490393f) * AT(5, 2) + F(0.865723f) * AT(7, 2));
		const Temp_Type X033 = D(F(0.022887f) * AT(1, 3) + F(-0.097545f) * AT(3, 3) + F(0.490393f) * AT(5, 3) + F(0.865723f) * AT(7, 3));
		const Temp_Type X034 = D(F(0.022887f) * AT(1, 4) + F(-0.097545f) * AT(3, 4) + F(0.490393f) * AT(5, 4) + F(0.865723f) * AT(7, 4));
		const Temp_Type X035 = D(F(0.022887f) * AT(1, 5) + F(-0.097545f) * AT(3, 5) + F(0.490393f) * AT(5, 5) + F(0.865723f) * AT(7, 5));
		const Temp_Type X036 = D(F(0.022887f) * AT(1, 6) + F(-0.097545f) * AT(3, 6) + F(0.490393f) * AT(5, 6) + F(0.865723f) * AT(7, 6));
		const Temp_Type X037 = D(F(0.022887f) * AT(1, 7) + F(-0.097545f) * AT(3, 7) + F(0.490393f) * AT(5, 7) + F(0.865723f) * AT(7, 7));

		// 4x4 = 4x8 times 8x4, matrix 1 is constant
		P.at(0, 0) = X000;
		P.at(0, 1) = D(X001 * F(0.415735f) + X003 * F(0.791065f) + X005 * F(-0.352443f) + X007 * F(0.277785f));
		P.at(0, 2) = X004;
		P.at(0, 3) = D(X001 * F(0.022887f) + X003 * F(-0.097545f) + X005 * F(0.490393f) + X007 * F(0.865723f));
		P.at(1, 0) = X010;
		P.at(1, 1) = D(X011 * F(0.415735f) + X013 * F(0.791065f) + X015 * F(-0.352443f) + X017 * F(0.277785f));
		P.at(1, 2) = X014;
		P.at(1, 3) = D(X011 * F(0.022887f) + X013 * F(-0.097545f) + X015 * F(0.490393f) + X017 * F(0.865723f));
		P.at(2, 0) = X020;
		P.at(2, 1) = D(X021 * F(0.415735f) + X023 * F(0.791065f) + X025 * F(-0.352443f) + X027 * F(0.277785f));
		P.at(2, 2) = X024;
		P.at(2, 3) = D(X021 * F(0.022887f) + X023 * F(-0.097545f) + X025 * F(0.490393f) + X027 * F(0.865723f));
		P.at(3, 0) = X030;
		P.at(3, 1) = D(X031 * F(0.415735f) + X033 * F(0.791065f) + X035 * F(-0.352443f) + X037 * F(0.277785f));
		P.at(3, 2) = X034;
		P.at(3, 3) = D(X031 * F(0.022887f) + X033 * F(-0.097545f) + X035 * F(0.490393f) + X037 * F(0.865723f));
		// 40 muls 24 adds

		// 4x4 = 4x8 times 8x4, matrix 1 is constant
		Q.at(0, 0) = D(X001 * F(0.906127f) + X003 * F(-0.318190f) + X005 * F(0.212608f) + X007 * F(-0.180240f));
		Q.at(0, 1) = X002;
		Q.at(0, 2) = D(X001 * F(-0.074658f) + X003 * F(0.513280f) + X005 * F(0.768178f) + X007 * F(-0.375330f));
		Q.at(0, 3) = X006;
		Q.at(1, 0) = D(X011 * F(0.906127f) + X013 * F(-0.318190f) + X015 * F(0.212608f) + X017 * F(-0.180240f));
		Q.at(1, 1) = X012;
		Q.at(1, 2) = D(X011 * F(-0.074658f) + X013 * F(0.513280f) + X015 * F(0.768178f) + X017 * F(-0.375330f));
		Q.at(1, 3) = X016;
		Q.at(2, 0) = D(X021 * F(0.906127f) + X023 * F(-0.318190f) + X025 * F(0.212608f) + X027 * F(-0.180240f));
		Q.at(2, 1) = X022;
		Q.at(2, 2) = D(X021 * F(-0.074658f) + X023 * F(0.513280f) + X025 * F(0.768178f) + X027 * F(-0.375330f));
		Q.at(2, 3) = X026;
		Q.at(3, 0) = D(X031 * F(0.906127f) + X033 * F(-0.318190f) + X035 * F(0.212608f) + X037 * F(-0.180240f));
		Q.at(3, 1) = X032;
		Q.at(3, 2) = D(X031 * F(-0.074658f) + X033 * F(0.513280f) + X035 * F(0.768178f) + X037 * F(-0.375330f));
		Q.at(3, 3) = X036;
		// 40 muls 24 adds
	}
};

template<int NUM_ROWS, int NUM_COLS>
struct R_S {
	static void calc(Matrix44& R, Matrix44& S, const jpgd_block_t* pSrc) {
		// 4x8 = 4x8 times 8x8, matrix 0 is constant
		const Temp_Type X100 = D(F(0.906127f) * AT(1, 0) + F(-0.318190f) * AT(3, 0) + F(0.212608f) * AT(5, 0) + F(-0.180240f) * AT(7, 0));
		const Temp_Type X101 = D(F(0.906127f) * AT(1, 1) + F(-0.318190f) * AT(3, 1) + F(0.212608f) * AT(5, 1) + F(-0.180240f) * AT(7, 1));
		const Temp_Type X102 = D(F(0.906127f) * AT(1, 2) + F(-0.318190f) * AT(3, 2) + F(0.212608f) * AT(5, 2) + F(-0.180240f) * AT(7, 2));
		const Temp_Type X103 = D(F(0.906127f) * AT(1, 3) + F(-0.318190f) * AT(3, 3) + F(0.212608f) * AT(5, 3) + F(-0.180240f) * AT(7, 3));
		const Temp_Type X104 = D(F(0.906127f) * AT(1, 4) + F(-0.318190f) * AT(3, 4) + F(0.212608f) * AT(5, 4) + F(-0.180240f) * AT(7, 4));
		const Temp_Type X105 = D(F(0.906127f) * AT(1, 5) + F(-0.318190f) * AT(3, 5) + F(0.212608f) * AT(5, 5) + F(-0.180240f) * AT(7, 5));
		const Temp_Type X106 = D(F(0.906127f) * AT(1, 6) + F(-0.318190f) * AT(3, 6) + F(0.212608f) * AT(5, 6) + F(-0.180240f) * AT(7, 6));
		const Temp_Type X107 = D(F(0.906127f) * AT(1, 7) + F(-0.318190f) * AT(3, 7) + F(0.212608f) * AT(5, 7) + F(-0.180240f) * AT(7, 7));
		const Temp_Type X110 = AT(2, 0);
		const Temp_Type X111 = AT(2, 1);
		const Temp_Type X112 = AT(2, 2);
		const Temp_Type X113 = AT(2, 3);
		const Temp_Type X114 = AT(2, 4);
		const Temp_Type X115 = AT(2, 5);
		const Temp_Type X116 = AT(2, 6);
		const Temp_Type X117 = AT(2, 7);
		const Temp_Type X120 = D(F(-0.074658f) * AT(1, 0) + F(0.513280f) * AT(3, 0) + F(0.768178f) * AT(5, 0) + F(-0.375330f) * AT(7, 0));
		const Temp_Type X121 = D(F(-0.074658f) * AT(1, 1) + F(0.513280f) * AT(3, 1) + F(0.768178f) * AT(5, 1) + F(-0.375330f) * AT(7, 1));
		const Temp_Type X122 = D(F(-0.074658f) * AT(1, 2) + F(0.513280f) * AT(3, 2) + F(0.768178f) * AT(5, 2) + F(-0.375330f) * AT(7, 2));
		const Temp_Type X123 = D(F(-0.074658f) * AT(1, 3) + F(0.513280f) * AT(3, 3) + F(0.768178f) * AT(5, 3) + F(-0.375330f) * AT(7, 3));
		const Temp_Type X124 = D(F(-0.074658f) * AT(1, 4) + F(0.513280f) * AT(3, 4) + F(0.768178f) * AT(5, 4) + F(-0.375330f) * AT(7, 4));
		const Temp_Type X125 = D(F(-0.074658f) * AT(1, 5) + F(0.513280f) * AT(3, 5) + F(0.768178f) * AT(5, 5) + F(-0.375330f) * AT(7, 5));
		const Temp_Type X126 = D(F(-0.074658f) * AT(1, 6) + F(0.513280f) * AT(3, 6) + F(0.768178f) * AT(5, 6) + F(-0.375330f) * AT(7, 6));
		const Temp_Type X127 = D(F(-0.074658f) * AT(1, 7) + F(0.513280f) * AT(3, 7) + F(0.768178f) * AT(5, 7) + F(-0.375330f) * AT(7, 7));
		const Temp_Type X130 = AT(6, 0);
		const Temp_Type X131 = AT(6, 1);
		const Temp_Type X132 = AT(6, 2);
		const Temp_Type X133 = AT(6, 3);
		const Temp_Type X134 = AT(6, 4);
		const Temp_Type X135 = AT(6, 5);
		const Temp_Type X136 = AT(6, 6);
		const Temp_Type X137 = AT(6, 7);
		// 80 muls 48 adds

		// 4x4 = 4x8 times 8x4, matrix 1 is constant
		R.at(0, 0) = X100;
		R.at(0, 1) = D(X101 * F(0.415735f) + X103 * F(0.791065f) + X105 * F(-0.352443f) + X107 * F(0.277785f));
		R.at(0, 2) = X104;
		R.at(0, 3) = D(X101 * F(0.022887f) + X103 * F(-0.097545f) + X105 * F(0.490393f) + X107 * F(0.865723f));
		R.at(1, 0) = X110;
		R.at(1, 1) = D(X111 * F(0.415735f) + X113 * F(0.791065f) + X115 * F(-0.352443f) + X117 * F(0.277785f));
		R.at(1, 2) = X114;
		R.at(1, 3) = D(X111 * F(0.022887f) + X113 * F(-0.097545f) + X115 * F(0.490393f) + X117 * F(0.865723f));
		R.at(2, 0) = X120;
		R.at(2, 1) = D(X121 * F(0.415735f) + X123 * F(0.791065f) + X125 * F(-0.352443f) + X127 * F(0.277785f));
		R.at(2, 2) = X124;
		R.at(2, 3) = D(X121 * F(0.022887f) + X123 * F(-0.097545f) + X125 * F(0.490393f) + X127 * F(0.865723f));
		R.at(3, 0) = X130;
		R.at(3, 1) = D(X131 * F(0.415735f) + X133 * F(0.791065f) + X135 * F(-0.352443f) + X137 * F(0.277785f));
		R.at(3, 2) = X134;
		R.at(3, 3) = D(X131 * F(0.022887f) + X133 * F(-0.097545f) + X135 * F(0.490393f) + X137 * F(0.865723f));
		// 40 muls 24 adds
		// 4x4 = 4x8 times 8x4, matrix 1 is constant
		S.at(0, 0) = D(X101 * F(0.906127f) + X103 * F(-0.318190f) + X105 * F(0.212608f) + X107 * F(-0.180240f));
		S.at(0, 1) = X102;
		S.at(0, 2) = D(X101 * F(-0.074658f) + X103 * F(0.513280f) + X105 * F(0.768178f) + X107 * F(-0.375330f));
		S.at(0, 3) = X106;
		S.at(1, 0) = D(X111 * F(0.906127f) + X113 * F(-0.318190f) + X115 * F(0.212608f) + X117 * F(-0.180240f));
		S.at(1, 1) = X112;
		S.at(1, 2) = D(X111 * F(-0.074658f) + X113 * F(0.513280f) + X115 * F(0.768178f) + X117 * F(-0.375330f));
		S.at(1, 3) = X116;
		S.at(2, 0) = D(X121 * F(0.906127f) + X123 * F(-0.318190f) + X125 * F(0.212608f) + X127 * F(-0.180240f));
		S.at(2, 1) = X122;
		S.at(2, 2) = D(X121 * F(-0.074658f) + X123 * F(0.513280f) + X125 * F(0.768178f) + X127 * F(-0.375330f));
		S.at(2, 3) = X126;
		S.at(3, 0) = D(X131 * F(0.906127f) + X133 * F(-0.318190f) + X135 * F(0.212608f) + X137 * F(-0.180240f));
		S.at(3, 1) = X132;
		S.at(3, 2) = D(X131 * F(-0.074658f) + X133 * F(0.513280f) + X135 * F(0.768178f) + X137 * F(-0.375330f));
		S.at(3, 3) = X136;
		// 40 muls 24 adds
	}
};
} // end namespace DCT_Upsample

// Unconditionally frees all allocated m_blocks.
void jpeg_decoder::free_all_blocks()
{
	m_pStream = NULL;
	for (mem_block *b = m_pMem_blocks; b; ) {
		mem_block *n = b->m_pNext;
		jpgd_free(b);
		b = n;
	}
	m_pMem_blocks = NULL;
}

// This method handles all errors. It will never return.
// It could easily be changed to use C++ exceptions.
JPGD_NORETURN void jpeg_decoder::stop_decoding(jpgd_status status)
{
	m_error_code = status;
	free_all_blocks();
	longjmp(m_jmp_state, status);
}

void *jpeg_decoder::alloc(size_t nSize, bool zero)
{
	nSize = (JPGD_MAX(nSize, 1) + 3) & ~3;
	char *rv = NULL;
	for (mem_block *b = m_pMem_blocks; b; b = b->m_pNext) {
		if ((b->m_used_count + nSize) <= b->m_size) {
			rv = b->m_data + b->m_used_count;
			b->m_used_count += nSize;
			break;
		}
	}
	if (!rv) {
		int capacity = JPGD_MAX(32768 - 256, (nSize + 2047) & ~2047);
		mem_block *b = (mem_block*)jpgd_malloc(sizeof(mem_block) + capacity);
		if (!b) {
			stop_decoding(JPGD_NOTENOUGHMEM);
		}
		b->m_pNext = m_pMem_blocks;
		m_pMem_blocks = b;
		b->m_used_count = nSize;
		b->m_size = capacity;
		rv = b->m_data;
	}
	if (zero) memset(rv, 0, nSize);
	return rv;
}

void jpeg_decoder::word_clear(void *p, uint16 c, uint n)
{
	uint8 *pD = (uint8*)p;
	const uint8 l = c & 0xFF, h = (c >> 8) & 0xFF;
	while (n) {
		pD[0] = l;
		pD[1] = h;
		pD += 2;
		n--;
	}
}

// Refill the input buffer.
// This method will sit in a loop until (A) the buffer is full or (B)
// the stream's read() method reports and end of file condition.
void jpeg_decoder::prep_in_buffer()
{
	m_in_buf_left = 0;
	m_pIn_buf_ofs = m_in_buf;

	if (m_eof_flag)
		return;

	do {
		int bytes_read = m_pStream->read(m_in_buf + m_in_buf_left, JPGD_IN_BUF_SIZE - m_in_buf_left, &m_eof_flag);
		if (bytes_read == -1)
			stop_decoding(JPGD_STREAM_READ);

		m_in_buf_left += bytes_read;
	} while ((m_in_buf_left < JPGD_IN_BUF_SIZE) && (!m_eof_flag));

	m_total_bytes_read += m_in_buf_left;

	// Pad the end of the block with M_EOI (prevents the decompressor from going off the rails if the stream is invalid).
	// (This dates way back to when this decompressor was written in C/asm, and the all-asm Huffman decoder did some fancy things to increase perf.)
	word_clear(m_pIn_buf_ofs + m_in_buf_left, 0xD9FF, 64);
}

// Read a Huffman code table.
void jpeg_decoder::read_dht_marker()
{
	int i, index, count;
	uint8 huff_num[17];
	uint8 huff_val[256];

	uint num_left = get_bits(16);

	if (num_left < 2)
		stop_decoding(JPGD_BAD_DHT_MARKER);

	num_left -= 2;

	while (num_left) {
		index = get_bits(8);

		huff_num[0] = 0;

		count = 0;

		for (i = 1; i <= 16; i++) {
			huff_num[i] = static_cast<uint8>(get_bits(8));
			count += huff_num[i];
		}

		if (count > 255)
			stop_decoding(JPGD_BAD_DHT_COUNTS);

		for (i = 0; i < count; i++)
			huff_val[i] = static_cast<uint8>(get_bits(8));

		i = 1 + 16 + count;

		if (num_left < (uint)i)
			stop_decoding(JPGD_BAD_DHT_MARKER);

		num_left -= i;

		if ((index & 0x10) > 0x10)
			stop_decoding(JPGD_BAD_DHT_INDEX);

		index = (index & 0x0F) + ((index & 0x10) >> 4) * (JPGD_MAX_HUFF_TABLES >> 1);

		if (index >= JPGD_MAX_HUFF_TABLES)
			stop_decoding(JPGD_BAD_DHT_INDEX);

		if (!m_huff_num[index])
			m_huff_num[index] = (uint8 *)alloc(17);

		if (!m_huff_val[index])
			m_huff_val[index] = (uint8 *)alloc(256);

		m_huff_ac[index] = (index & 0x10) != 0;
		memcpy(m_huff_num[index], huff_num, 17);
		memcpy(m_huff_val[index], huff_val, 256);
	}
}

// Read a quantization table.
void jpeg_decoder::read_dqt_marker()
{
	int n, i, prec;
	uint num_left;
	uint temp;

	num_left = get_bits(16);

	if (num_left < 2)
		stop_decoding(JPGD_BAD_DQT_MARKER);

	num_left -= 2;

	while (num_left) {
		n = get_bits(8);
		prec = n >> 4;
		n &= 0x0F;

		if (n >= JPGD_MAX_QUANT_TABLES)
			stop_decoding(JPGD_BAD_DQT_TABLE);

		if (!m_quant[n])
			m_quant[n] = (jpgd_quant_t *)alloc(64 * sizeof(jpgd_quant_t));

		// read quantization entries, in zag order
		for (i = 0; i < 64; i++) {
			temp = get_bits(8);

			if (prec)
				temp = (temp << 8) + get_bits(8);

			m_quant[n][i] = static_cast<jpgd_quant_t>(temp);
		}

		i = 64 + 1;

		if (prec)
			i += 64;

		if (num_left < (uint)i)
			stop_decoding(JPGD_BAD_DQT_LENGTH);

		num_left -= i;
	}
}

// Read the start of frame (SOF) marker.
void jpeg_decoder::read_sof_marker()
{
	int i;
	uint num_left;

	num_left = get_bits(16);

	if (get_bits(8) != 8)   /* precision: sorry, only 8-bit precision is supported right now */
		stop_decoding(JPGD_BAD_PRECISION);

	m_image_y_size = get_bits(16);

	if ((m_image_y_size < 1) || (m_image_y_size > JPGD_MAX_HEIGHT))
		stop_decoding(JPGD_BAD_HEIGHT);

	m_image_x_size = get_bits(16);

	if ((m_image_x_size < 1) || (m_image_x_size > JPGD_MAX_WIDTH))
		stop_decoding(JPGD_BAD_WIDTH);

	m_comps_in_frame = get_bits(8);

	if (m_comps_in_frame > JPGD_MAX_COMPONENTS)
		stop_decoding(JPGD_TOO_MANY_COMPONENTS);

	if (num_left != (uint)(m_comps_in_frame * 3 + 8))
		stop_decoding(JPGD_BAD_SOF_LENGTH);

	for (i = 0; i < m_comps_in_frame; i++) {
		m_comp_ident[i]  = get_bits(8);
		m_comp_h_samp[i] = get_bits(4);
		m_comp_v_samp[i] = get_bits(4);
		m_comp_quant[i]  = get_bits(8);
	}
}

// Used to skip unrecognized markers.
void jpeg_decoder::skip_variable_marker()
{
	uint num_left;

	num_left = get_bits(16);

	if (num_left < 2)
		stop_decoding(JPGD_BAD_VARIABLE_MARKER);

	num_left -= 2;

	while (num_left) {
		get_bits(8);
		num_left--;
	}
}

// Read a define restart interval (DRI) marker.
void jpeg_decoder::read_dri_marker()
{
	if (get_bits(16) != 4)
		stop_decoding(JPGD_BAD_DRI_LENGTH);

	m_restart_interval = get_bits(16);
}

// Read a start of scan (SOS) marker.
void jpeg_decoder::read_sos_marker()
{
	uint num_left;
	int i, ci, n, c, cc;

	num_left = get_bits(16);

	n = get_bits(8);

	m_comps_in_scan = n;

	num_left -= 3;

	if ( (num_left != (uint)(n * 2 + 3)) || (n < 1) || (n > JPGD_MAX_COMPS_IN_SCAN) )
		stop_decoding(JPGD_BAD_SOS_LENGTH);

	for (i = 0; i < n; i++) {
		cc = get_bits(8);
		c = get_bits(8);
		num_left -= 2;

		for (ci = 0; ci < m_comps_in_frame; ci++)
			if (cc == m_comp_ident[ci])
				break;

		if (ci >= m_comps_in_frame)
			stop_decoding(JPGD_BAD_SOS_COMP_ID);

		m_comp_list[i]    = ci;
		m_comp_dc_tab[ci] = (c >> 4) & 15;
		m_comp_ac_tab[ci] = (c & 15) + (JPGD_MAX_HUFF_TABLES >> 1);
	}

	m_spectral_start  = get_bits(8);
	m_spectral_end    = get_bits(8);
	m_successive_high = get_bits(4);
	m_successive_low  = get_bits(4);

	if (!m_progressive_flag) {
		m_spectral_start = 0;
		m_spectral_end = 63;
	}

	num_left -= 3;

	while (num_left) {                /* read past whatever is num_left */
		get_bits(8);
		num_left--;
	}
}

// Finds the next marker.
int jpeg_decoder::next_marker()
{
	uint c, bytes;

	bytes = 0;

	do {
		do {
			bytes++;
			c = get_bits(8);
		} while (c != 0xFF);

		do {
			c = get_bits(8);
		} while (c == 0xFF);

	} while (c == 0);

	// If bytes > 0 here, there where extra bytes before the marker (not good).

	return c;
}

// Process markers. Returns when an SOFx, SOI, EOI, or SOS marker is
// encountered.
int jpeg_decoder::process_markers()
{
	int c;

	for ( ; ; ) {
		c = next_marker();

		switch (c) {
		case M_SOF0:
		case M_SOF1:
		case M_SOF2:
		case M_SOF3:
		case M_SOF5:
		case M_SOF6:
		case M_SOF7:
//      case M_JPG:
		case M_SOF9:
		case M_SOF10:
		case M_SOF11:
		case M_SOF13:
		case M_SOF14:
		case M_SOF15:
		case M_SOI:
		case M_EOI:
		case M_SOS: {
			return c;
		}
		case M_DHT: {
			read_dht_marker();
			break;
		}
		// No arithmitic support - dumb patents!
		case M_DAC: {
			stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT);
			break;
		}
		case M_DQT: {
			read_dqt_marker();
			break;
		}
		case M_DRI: {
			read_dri_marker();
			break;
		}
		//case M_APP0:  /* no need to read the JFIF marker */

		case M_JPG:
		case M_RST0:    /* no parameters */
		case M_RST1:
		case M_RST2:
		case M_RST3:
		case M_RST4:
		case M_RST5:
		case M_RST6:
		case M_RST7:
		case M_TEM: {
			stop_decoding(JPGD_UNEXPECTED_MARKER);
			break;
		}
		default: {  /* must be DNL, DHP, EXP, APPn, JPGn, COM, or RESn or APP0 */
			skip_variable_marker();
			break;
		}
		}
	}
}

// Finds the start of image (SOI) marker.
// This code is rather defensive: it only checks the first 512 bytes to avoid
// false positives.
void jpeg_decoder::locate_soi_marker()
{
	uint lastchar, thischar;
	uint bytesleft;

	lastchar = get_bits(8);

	thischar = get_bits(8);

	/* ok if it's a normal JPEG file without a special header */

	if ((lastchar == 0xFF) && (thischar == M_SOI))
		return;

	bytesleft = 4096; //512;

	for ( ; ; ) {
		if (--bytesleft == 0)
			stop_decoding(JPGD_NOT_JPEG);

		lastchar = thischar;

		thischar = get_bits(8);

		if (lastchar == 0xFF) {
			if (thischar == M_SOI)
				break;
			else if (thischar == M_EOI) // get_bits will keep returning M_EOI if we read past the end
				stop_decoding(JPGD_NOT_JPEG);
		}
	}

	// Check the next character after marker: if it's not 0xFF, it can't be the start of the next marker, so the file is bad.
	thischar = (m_bit_buf >> 24) & 0xFF;

	if (thischar != 0xFF)
		stop_decoding(JPGD_NOT_JPEG);
}

// Find a start of frame (SOF) marker.
void jpeg_decoder::locate_sof_marker()
{
	locate_soi_marker();

	int c = process_markers();

	switch (c) {
	case M_SOF2:
		m_progressive_flag = JPGD_TRUE;
	case M_SOF0:  /* baseline DCT */
	case M_SOF1: { /* extended sequential DCT */
		read_sof_marker();
		break;
	}
	case M_SOF9: { /* Arithmitic coding */
		stop_decoding(JPGD_NO_ARITHMITIC_SUPPORT);
		break;
	}
	default: {
		stop_decoding(JPGD_UNSUPPORTED_MARKER);
		break;
	}
	}
}

// Find a start of scan (SOS) marker.
int jpeg_decoder::locate_sos_marker()
{
	int c;

	c = process_markers();

	if (c == M_EOI)
		return JPGD_FALSE;
	else if (c != M_SOS)
		stop_decoding(JPGD_UNEXPECTED_MARKER);

	read_sos_marker();

	return JPGD_TRUE;
}

// Reset everything to default/uninitialized state.
void jpeg_decoder::init(jpeg_decoder_stream *pStream)
{
	m_pMem_blocks = NULL;
	m_error_code = JPGD_SUCCESS;
	m_ready_flag = false;
	m_image_x_size = m_image_y_size = 0;
	m_pStream = pStream;
	m_progressive_flag = JPGD_FALSE;

	memset(m_huff_ac, 0, sizeof(m_huff_ac));
	memset(m_huff_num, 0, sizeof(m_huff_num));
	memset(m_huff_val, 0, sizeof(m_huff_val));
	memset(m_quant, 0, sizeof(m_quant));

	m_scan_type = 0;
	m_comps_in_frame = 0;

	memset(m_comp_h_samp, 0, sizeof(m_comp_h_samp));
	memset(m_comp_v_samp, 0, sizeof(m_comp_v_samp));
	memset(m_comp_quant, 0, sizeof(m_comp_quant));
	memset(m_comp_ident, 0, sizeof(m_comp_ident));
	memset(m_comp_h_blocks, 0, sizeof(m_comp_h_blocks));
	memset(m_comp_v_blocks, 0, sizeof(m_comp_v_blocks));

	m_comps_in_scan = 0;
	memset(m_comp_list, 0, sizeof(m_comp_list));
	memset(m_comp_dc_tab, 0, sizeof(m_comp_dc_tab));
	memset(m_comp_ac_tab, 0, sizeof(m_comp_ac_tab));

	m_spectral_start = 0;
	m_spectral_end = 0;
	m_successive_low = 0;
	m_successive_high = 0;
	m_max_mcu_x_size = 0;
	m_max_mcu_y_size = 0;
	m_blocks_per_mcu = 0;
	m_max_blocks_per_row = 0;
	m_mcus_per_row = 0;
	m_mcus_per_col = 0;
	m_expanded_blocks_per_component = 0;
	m_expanded_blocks_per_mcu = 0;
	m_expanded_blocks_per_row = 0;
	m_freq_domain_chroma_upsample = false;

	memset(m_mcu_org, 0, sizeof(m_mcu_org));

	m_total_lines_left = 0;
	m_mcu_lines_left = 0;
	m_real_dest_bytes_per_scan_line = 0;
	m_dest_bytes_per_scan_line = 0;
	m_dest_bytes_per_pixel = 0;

	memset(m_pHuff_tabs, 0, sizeof(m_pHuff_tabs));

	memset(m_dc_coeffs, 0, sizeof(m_dc_coeffs));
	memset(m_ac_coeffs, 0, sizeof(m_ac_coeffs));
	memset(m_block_y_mcu, 0, sizeof(m_block_y_mcu));

	m_eob_run = 0;

	memset(m_block_y_mcu, 0, sizeof(m_block_y_mcu));

	m_pIn_buf_ofs = m_in_buf;
	m_in_buf_left = 0;
	m_eof_flag = false;
	m_tem_flag = 0;

	memset(m_in_buf_pad_start, 0, sizeof(m_in_buf_pad_start));
	memset(m_in_buf, 0, sizeof(m_in_buf));
	memset(m_in_buf_pad_end, 0, sizeof(m_in_buf_pad_end));

	m_restart_interval = 0;
	m_restarts_left    = 0;
	m_next_restart_num = 0;

	m_max_mcus_per_row = 0;
	m_max_blocks_per_mcu = 0;
	m_max_mcus_per_col = 0;

	memset(m_last_dc_val, 0, sizeof(m_last_dc_val));
	m_pMCU_coefficients = NULL;
	m_pSample_buf = NULL;

	m_total_bytes_read = 0;

	m_pScan_line_0 = NULL;
	m_pScan_line_1 = NULL;

	// Ready the input buffer.
	prep_in_buffer();

	// Prime the bit buffer.
	m_bits_left = 16;
	m_bit_buf = 0;

	get_bits(16);
	get_bits(16);

	for (int i = 0; i < JPGD_MAX_BLOCKS_PER_MCU; i++)
		m_mcu_block_max_zag[i] = 64;
}

#define SCALEBITS 16
#define ONE_HALF  ((int) 1 << (SCALEBITS-1))
#define FIX(x)    ((int) ((x) * (1L<<SCALEBITS) + 0.5f))

// Create a few tables that allow us to quickly convert YCbCr to RGB.
void jpeg_decoder::create_look_ups()
{
	for (int i = 0; i <= 255; i++) {
		int k = i - 128;
		m_crr[i] = ( FIX(1.40200f)  * k + ONE_HALF) >> SCALEBITS;
		m_cbb[i] = ( FIX(1.77200f)  * k + ONE_HALF) >> SCALEBITS;
		m_crg[i] = (-FIX(0.71414f)) * k;
		m_cbg[i] = (-FIX(0.34414f)) * k + ONE_HALF;
	}
}

// This method throws back into the stream any bytes that where read
// into the bit buffer during initial marker scanning.
void jpeg_decoder::fix_in_buffer()
{
	// In case any 0xFF's where pulled into the buffer during marker scanning.
	JPGD_ASSERT((m_bits_left & 7) == 0);

	if (m_bits_left == 16)
		stuff_char( (uint8)(m_bit_buf & 0xFF));

	if (m_bits_left >= 8)
		stuff_char( (uint8)((m_bit_buf >> 8) & 0xFF));

	stuff_char((uint8)((m_bit_buf >> 16) & 0xFF));
	stuff_char((uint8)((m_bit_buf >> 24) & 0xFF));

	m_bits_left = 16;
	get_bits_no_markers(16);
	get_bits_no_markers(16);
}

void jpeg_decoder::transform_mcu(int mcu_row)
{
	jpgd_block_t* pSrc_ptr = m_pMCU_coefficients;
	uint8* pDst_ptr = m_pSample_buf + mcu_row * m_blocks_per_mcu * 64;

	for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) {
		idct(pSrc_ptr, pDst_ptr, m_mcu_block_max_zag[mcu_block]);
		pSrc_ptr += 64;
		pDst_ptr += 64;
	}
}

static const uint8 s_max_rc[64] = {
	17, 18, 34, 50, 50, 51, 52, 52, 52, 68, 84, 84, 84, 84, 85, 86, 86, 86, 86, 86,
	102, 118, 118, 118, 118, 118, 118, 119, 120, 120, 120, 120, 120, 120, 120, 136,
	136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136,
	136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136, 136
};

void jpeg_decoder::transform_mcu_expand(int mcu_row)
{
	jpgd_block_t* pSrc_ptr = m_pMCU_coefficients;
	uint8* pDst_ptr = m_pSample_buf + mcu_row * m_expanded_blocks_per_mcu * 64;

	// Y IDCT
	int mcu_block;
	for (mcu_block = 0; mcu_block < m_expanded_blocks_per_component; mcu_block++) {
		idct(pSrc_ptr, pDst_ptr, m_mcu_block_max_zag[mcu_block]);
		pSrc_ptr += 64;
		pDst_ptr += 64;
	}

	// Chroma IDCT, with upsampling
	jpgd_block_t temp_block[64];

	for (int i = 0; i < 2; i++) {
		DCT_Upsample::Matrix44 P, Q, R, S;

		JPGD_ASSERT(m_mcu_block_max_zag[mcu_block] >= 1);
		JPGD_ASSERT(m_mcu_block_max_zag[mcu_block] <= 64);

		int max_zag = m_mcu_block_max_zag[mcu_block++] - 1;
		if (max_zag <= 0) max_zag = 0; // should never happen, only here to shut up static analysis
		switch (s_max_rc[max_zag]) {
		case 1*16+1:
			DCT_Upsample::P_Q<1, 1>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<1, 1>::calc(R, S, pSrc_ptr);
			break;
		case 1*16+2:
			DCT_Upsample::P_Q<1, 2>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<1, 2>::calc(R, S, pSrc_ptr);
			break;
		case 2*16+2:
			DCT_Upsample::P_Q<2, 2>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<2, 2>::calc(R, S, pSrc_ptr);
			break;
		case 3*16+2:
			DCT_Upsample::P_Q<3, 2>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<3, 2>::calc(R, S, pSrc_ptr);
			break;
		case 3*16+3:
			DCT_Upsample::P_Q<3, 3>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<3, 3>::calc(R, S, pSrc_ptr);
			break;
		case 3*16+4:
			DCT_Upsample::P_Q<3, 4>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<3, 4>::calc(R, S, pSrc_ptr);
			break;
		case 4*16+4:
			DCT_Upsample::P_Q<4, 4>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<4, 4>::calc(R, S, pSrc_ptr);
			break;
		case 5*16+4:
			DCT_Upsample::P_Q<5, 4>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<5, 4>::calc(R, S, pSrc_ptr);
			break;
		case 5*16+5:
			DCT_Upsample::P_Q<5, 5>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<5, 5>::calc(R, S, pSrc_ptr);
			break;
		case 5*16+6:
			DCT_Upsample::P_Q<5, 6>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<5, 6>::calc(R, S, pSrc_ptr);
			break;
		case 6*16+6:
			DCT_Upsample::P_Q<6, 6>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<6, 6>::calc(R, S, pSrc_ptr);
			break;
		case 7*16+6:
			DCT_Upsample::P_Q<7, 6>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<7, 6>::calc(R, S, pSrc_ptr);
			break;
		case 7*16+7:
			DCT_Upsample::P_Q<7, 7>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<7, 7>::calc(R, S, pSrc_ptr);
			break;
		case 7*16+8:
			DCT_Upsample::P_Q<7, 8>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<7, 8>::calc(R, S, pSrc_ptr);
			break;
		case 8*16+8:
			DCT_Upsample::P_Q<8, 8>::calc(P, Q, pSrc_ptr);
			DCT_Upsample::R_S<8, 8>::calc(R, S, pSrc_ptr);
			break;
		default:
			JPGD_ASSERT(false);
		}

		DCT_Upsample::Matrix44 a(P + Q);
		P -= Q;
		DCT_Upsample::Matrix44& b = P;
		DCT_Upsample::Matrix44 c(R + S);
		R -= S;
		DCT_Upsample::Matrix44& d = R;

		DCT_Upsample::Matrix44::add_and_store(temp_block, a, c);
		idct_4x4(temp_block, pDst_ptr);
		pDst_ptr += 64;

		DCT_Upsample::Matrix44::sub_and_store(temp_block, a, c);
		idct_4x4(temp_block, pDst_ptr);
		pDst_ptr += 64;

		DCT_Upsample::Matrix44::add_and_store(temp_block, b, d);
		idct_4x4(temp_block, pDst_ptr);
		pDst_ptr += 64;

		DCT_Upsample::Matrix44::sub_and_store(temp_block, b, d);
		idct_4x4(temp_block, pDst_ptr);
		pDst_ptr += 64;

		pSrc_ptr += 64;
	}
}

// Loads and dequantizes the next row of (already decoded) coefficients.
// Progressive images only.
void jpeg_decoder::load_next_row()
{
	int i;
	jpgd_block_t *p;
	jpgd_quant_t *q;
	int mcu_row, mcu_block, row_block = 0;
	int component_num, component_id;
	int block_x_mcu[JPGD_MAX_COMPONENTS];

	memset(block_x_mcu, 0, JPGD_MAX_COMPONENTS * sizeof(int));

	for (mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) {
		int block_x_mcu_ofs = 0, block_y_mcu_ofs = 0;

		for (mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) {
			component_id = m_mcu_org[mcu_block];
			q = m_quant[m_comp_quant[component_id]];

			p = m_pMCU_coefficients + 64 * mcu_block;

			jpgd_block_t* pAC = coeff_buf_getp(m_ac_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs);
			jpgd_block_t* pDC = coeff_buf_getp(m_dc_coeffs[component_id], block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs);
			p[0] = pDC[0];
			memcpy(&p[1], &pAC[1], 63 * sizeof(jpgd_block_t));

			for (i = 63; i > 0; i--)
				if (p[g_ZAG[i]])
					break;

			m_mcu_block_max_zag[mcu_block] = i + 1;

			for ( ; i >= 0; i--)
				if (p[g_ZAG[i]])
					p[g_ZAG[i]] = static_cast<jpgd_block_t>(p[g_ZAG[i]] * q[i]);

			row_block++;

			if (m_comps_in_scan == 1)
				block_x_mcu[component_id]++;
			else {
				if (++block_x_mcu_ofs == m_comp_h_samp[component_id]) {
					block_x_mcu_ofs = 0;

					if (++block_y_mcu_ofs == m_comp_v_samp[component_id]) {
						block_y_mcu_ofs = 0;

						block_x_mcu[component_id] += m_comp_h_samp[component_id];
					}
				}
			}
		}

		if (m_freq_domain_chroma_upsample)
			transform_mcu_expand(mcu_row);
		else
			transform_mcu(mcu_row);
	}

	if (m_comps_in_scan == 1)
		m_block_y_mcu[m_comp_list[0]]++;
	else {
		for (component_num = 0; component_num < m_comps_in_scan; component_num++) {
			component_id = m_comp_list[component_num];

			m_block_y_mcu[component_id] += m_comp_v_samp[component_id];
		}
	}
}

// Restart interval processing.
void jpeg_decoder::process_restart()
{
	int i;
	int c = 0;

	// Align to a byte boundry
	// FIXME: Is this really necessary? get_bits_no_markers() never reads in markers!
	//get_bits_no_markers(m_bits_left & 7);

	// Let's scan a little bit to find the marker, but not _too_ far.
	// 1536 is a "fudge factor" that determines how much to scan.
	for (i = 1536; i > 0; i--)
		if (get_char() == 0xFF)
			break;

	if (i == 0)
		stop_decoding(JPGD_BAD_RESTART_MARKER);

	for ( ; i > 0; i--)
		if ((c = get_char()) != 0xFF)
			break;

	if (i == 0)
		stop_decoding(JPGD_BAD_RESTART_MARKER);

	// Is it the expected marker? If not, something bad happened.
	if (c != (m_next_restart_num + M_RST0))
		stop_decoding(JPGD_BAD_RESTART_MARKER);

	// Reset each component's DC prediction values.
	memset(&m_last_dc_val, 0, m_comps_in_frame * sizeof(uint));

	m_eob_run = 0;

	m_restarts_left = m_restart_interval;

	m_next_restart_num = (m_next_restart_num + 1) & 7;

	// Get the bit buffer going again...

	m_bits_left = 16;
	get_bits_no_markers(16);
	get_bits_no_markers(16);
}

static inline int dequantize_ac(int c, int q)
{
	c *= q;
	return c;
}

// Decodes and dequantizes the next row of coefficients.
void jpeg_decoder::decode_next_row()
{
	int row_block = 0;

	for (int mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) {
		if ((m_restart_interval) && (m_restarts_left == 0))
			process_restart();

		jpgd_block_t* p = m_pMCU_coefficients;
		for (int mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++, p += 64) {
			int component_id = m_mcu_org[mcu_block];
			jpgd_quant_t* q = m_quant[m_comp_quant[component_id]];

			int r, s;
			s = huff_decode(m_pHuff_tabs[m_comp_dc_tab[component_id]], r);
			s = JPGD_HUFF_EXTEND(r, s);

			m_last_dc_val[component_id] = (s += m_last_dc_val[component_id]);

			p[0] = static_cast<jpgd_block_t>(s * q[0]);

			int prev_num_set = m_mcu_block_max_zag[mcu_block];

			huff_tables *pH = m_pHuff_tabs[m_comp_ac_tab[component_id]];

			int k;
			for (k = 1; k < 64; k++) {
				int extra_bits;
				s = huff_decode(pH, extra_bits);

				r = s >> 4;
				s &= 15;

				if (s) {
					if (r) {
						if ((k + r) > 63)
							stop_decoding(JPGD_DECODE_ERROR);

						if (k < prev_num_set) {
							int n = JPGD_MIN(r, prev_num_set - k);
							int kt = k;
							while (n--)
								p[g_ZAG[kt++]] = 0;
						}

						k += r;
					}

					s = JPGD_HUFF_EXTEND(extra_bits, s);

					JPGD_ASSERT(k < 64);

					p[g_ZAG[k]] = static_cast<jpgd_block_t>(dequantize_ac(s, q[k])); //s * q[k];
				} else {
					if (r == 15) {
						if ((k + 16) > 64)
							stop_decoding(JPGD_DECODE_ERROR);

						if (k < prev_num_set) {
							int n = JPGD_MIN(16, prev_num_set - k);
							int kt = k;
							while (n--) {
								JPGD_ASSERT(kt <= 63);
								p[g_ZAG[kt++]] = 0;
							}
						}

						k += 16 - 1; // - 1 because the loop counter is k
						JPGD_ASSERT(p[g_ZAG[k]] == 0);
					} else
						break;
				}
			}

			if (k < prev_num_set) {
				int kt = k;
				while (kt < prev_num_set)
					p[g_ZAG[kt++]] = 0;
			}

			m_mcu_block_max_zag[mcu_block] = k;

			row_block++;
		}

		if (m_freq_domain_chroma_upsample)
			transform_mcu_expand(mcu_row);
		else
			transform_mcu(mcu_row);

		m_restarts_left--;
	}
}

// YCbCr H1V1 (1x1:1:1, 3 m_blocks per MCU) to RGB
void jpeg_decoder::H1V1Convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;
	uint8 *d = m_pScan_line_0;
	uint8 *s = m_pSample_buf + row * 8;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		for (int j = 0; j < 8; j++) {
			int y = s[j];
			int cb = s[64+j];
			int cr = s[128+j];

			d[0] = clamp(y + m_crr[cr]);
			d[1] = clamp(y + ((m_crg[cr] + m_cbg[cb]) >> 16));
			d[2] = clamp(y + m_cbb[cb]);
			d[3] = 255;

			d += 4;
		}

		s += 64*3;
	}
}

// YCbCr H2V1 (2x1:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H2V1Convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;
	uint8 *d0 = m_pScan_line_0;
	uint8 *y = m_pSample_buf + row * 8;
	uint8 *c = m_pSample_buf + 2*64 + row * 8;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		for (int l = 0; l < 2; l++) {
			for (int j = 0; j < 4; j++) {
				int cb = c[0];
				int cr = c[64];

				int rc = m_crr[cr];
				int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
				int bc = m_cbb[cb];

				int yy = y[j<<1];
				d0[0] = clamp(yy+rc);
				d0[1] = clamp(yy+gc);
				d0[2] = clamp(yy+bc);
				d0[3] = 255;

				yy = y[(j<<1)+1];
				d0[4] = clamp(yy+rc);
				d0[5] = clamp(yy+gc);
				d0[6] = clamp(yy+bc);
				d0[7] = 255;

				d0 += 8;

				c++;
			}
			y += 64;
		}

		y += 64*4 - 64*2;
		c += 64*4 - 8;
	}
}

// YCbCr H2V1 (1x2:1:1, 4 m_blocks per MCU) to RGB
void jpeg_decoder::H1V2Convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;
	uint8 *d0 = m_pScan_line_0;
	uint8 *d1 = m_pScan_line_1;
	uint8 *y;
	uint8 *c;

	if (row < 8)
		y = m_pSample_buf + row * 8;
	else
		y = m_pSample_buf + 64*1 + (row & 7) * 8;

	c = m_pSample_buf + 64*2 + (row >> 1) * 8;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		for (int j = 0; j < 8; j++) {
			int cb = c[0+j];
			int cr = c[64+j];

			int rc = m_crr[cr];
			int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
			int bc = m_cbb[cb];

			int yy = y[j];
			d0[0] = clamp(yy+rc);
			d0[1] = clamp(yy+gc);
			d0[2] = clamp(yy+bc);
			d0[3] = 255;

			yy = y[8+j];
			d1[0] = clamp(yy+rc);
			d1[1] = clamp(yy+gc);
			d1[2] = clamp(yy+bc);
			d1[3] = 255;

			d0 += 4;
			d1 += 4;
		}

		y += 64*4;
		c += 64*4;
	}
}

// YCbCr H2V2 (2x2:1:1, 6 m_blocks per MCU) to RGB
void jpeg_decoder::H2V2Convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;
	uint8 *d0 = m_pScan_line_0;
	uint8 *d1 = m_pScan_line_1;
	uint8 *y;
	uint8 *c;

	if (row < 8)
		y = m_pSample_buf + row * 8;
	else
		y = m_pSample_buf + 64*2 + (row & 7) * 8;

	c = m_pSample_buf + 64*4 + (row >> 1) * 8;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		for (int l = 0; l < 2; l++) {
			for (int j = 0; j < 8; j += 2) {
				int cb = c[0];
				int cr = c[64];

				int rc = m_crr[cr];
				int gc = ((m_crg[cr] + m_cbg[cb]) >> 16);
				int bc = m_cbb[cb];

				int yy = y[j];
				d0[0] = clamp(yy+rc);
				d0[1] = clamp(yy+gc);
				d0[2] = clamp(yy+bc);
				d0[3] = 255;

				yy = y[j+1];
				d0[4] = clamp(yy+rc);
				d0[5] = clamp(yy+gc);
				d0[6] = clamp(yy+bc);
				d0[7] = 255;

				yy = y[j+8];
				d1[0] = clamp(yy+rc);
				d1[1] = clamp(yy+gc);
				d1[2] = clamp(yy+bc);
				d1[3] = 255;

				yy = y[j+8+1];
				d1[4] = clamp(yy+rc);
				d1[5] = clamp(yy+gc);
				d1[6] = clamp(yy+bc);
				d1[7] = 255;

				d0 += 8;
				d1 += 8;

				c++;
			}
			y += 64;
		}

		y += 64*6 - 64*2;
		c += 64*6 - 8;
	}
}

// Y (1 block per MCU) to 8-bit grayscale
void jpeg_decoder::gray_convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;
	uint8 *d = m_pScan_line_0;
	uint8 *s = m_pSample_buf + row * 8;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		*(uint *)d = *(uint *)s;
		*(uint *)(&d[4]) = *(uint *)(&s[4]);

		s += 64;
		d += 8;
	}
}

void jpeg_decoder::expanded_convert()
{
	int row = m_max_mcu_y_size - m_mcu_lines_left;

	uint8* Py = m_pSample_buf + (row / 8) * 64 * m_comp_h_samp[0] + (row & 7) * 8;

	uint8* d = m_pScan_line_0;

	for (int i = m_max_mcus_per_row; i > 0; i--) {
		for (int k = 0; k < m_max_mcu_x_size; k += 8) {
			const int Y_ofs = k * 8;
			const int Cb_ofs = Y_ofs + 64 * m_expanded_blocks_per_component;
			const int Cr_ofs = Y_ofs + 64 * m_expanded_blocks_per_component * 2;
			for (int j = 0; j < 8; j++) {
				int y = Py[Y_ofs + j];
				int cb = Py[Cb_ofs + j];
				int cr = Py[Cr_ofs + j];

				d[0] = clamp(y + m_crr[cr]);
				d[1] = clamp(y + ((m_crg[cr] + m_cbg[cb]) >> 16));
				d[2] = clamp(y + m_cbb[cb]);
				d[3] = 255;

				d += 4;
			}
		}

		Py += 64 * m_expanded_blocks_per_mcu;
	}
}

// Find end of image (EOI) marker, so we can return to the user the exact size of the input stream.
void jpeg_decoder::find_eoi()
{
	if (!m_progressive_flag) {
		// Attempt to read the EOI marker.
		//get_bits_no_markers(m_bits_left & 7);

		// Prime the bit buffer
		m_bits_left = 16;
		get_bits(16);
		get_bits(16);

		// The next marker _should_ be EOI
		process_markers();
	}

	m_total_bytes_read -= m_in_buf_left;
}

int jpeg_decoder::decode(const void** pScan_line, uint* pScan_line_len)
{
	if ((m_error_code) || (!m_ready_flag))
		return JPGD_FAILED;

	if (m_total_lines_left == 0)
		return JPGD_DONE;

	if (m_mcu_lines_left == 0) {
		if (setjmp(m_jmp_state))
			return JPGD_FAILED;

		if (m_progressive_flag)
			load_next_row();
		else
			decode_next_row();

		// Find the EOI marker if that was the last row.
		if (m_total_lines_left <= m_max_mcu_y_size)
			find_eoi();

		m_mcu_lines_left = m_max_mcu_y_size;
	}

	if (m_freq_domain_chroma_upsample) {
		expanded_convert();
		*pScan_line = m_pScan_line_0;
	} else {
		switch (m_scan_type) {
		case JPGD_YH2V2: {
			if ((m_mcu_lines_left & 1) == 0) {
				H2V2Convert();
				*pScan_line = m_pScan_line_0;
			} else
				*pScan_line = m_pScan_line_1;

			break;
		}
		case JPGD_YH2V1: {
			H2V1Convert();
			*pScan_line = m_pScan_line_0;
			break;
		}
		case JPGD_YH1V2: {
			if ((m_mcu_lines_left & 1) == 0) {
				H1V2Convert();
				*pScan_line = m_pScan_line_0;
			} else
				*pScan_line = m_pScan_line_1;

			break;
		}
		case JPGD_YH1V1: {
			H1V1Convert();
			*pScan_line = m_pScan_line_0;
			break;
		}
		case JPGD_GRAYSCALE: {
			gray_convert();
			*pScan_line = m_pScan_line_0;

			break;
		}
		}
	}

	*pScan_line_len = m_real_dest_bytes_per_scan_line;

	m_mcu_lines_left--;
	m_total_lines_left--;

	return JPGD_SUCCESS;
}

// Creates the tables needed for efficient Huffman decoding.
void jpeg_decoder::make_huff_table(int index, huff_tables *pH)
{
	int p, i, l, si;
	uint8 huffsize[257];
	uint huffcode[257];
	uint code;
	uint subtree;
	int code_size;
	int lastp;
	int nextfreeentry;
	int currententry;

	pH->ac_table = m_huff_ac[index] != 0;

	p = 0;

	for (l = 1; l <= 16; l++) {
		for (i = 1; i <= m_huff_num[index][l]; i++)
			huffsize[p++] = static_cast<uint8>(l);
	}

	huffsize[p] = 0;

	lastp = p;

	code = 0;
	si = huffsize[0];
	p = 0;

	while (huffsize[p]) {
		while (huffsize[p] == si) {
			huffcode[p++] = code;
			code++;
		}

		code <<= 1;
		si++;
	}

	memset(pH->look_up, 0, sizeof(pH->look_up));
	memset(pH->look_up2, 0, sizeof(pH->look_up2));
	memset(pH->tree, 0, sizeof(pH->tree));
	memset(pH->code_size, 0, sizeof(pH->code_size));

	nextfreeentry = -1;

	p = 0;

	while (p < lastp) {
		i = m_huff_val[index][p];
		code = huffcode[p];
		code_size = huffsize[p];

		pH->code_size[i] = static_cast<uint8>(code_size);

		if (code_size <= 8) {
			code <<= (8 - code_size);

			for (l = 1 << (8 - code_size); l > 0; l--) {
				JPGD_ASSERT(i < 256);

				pH->look_up[code] = i;

				bool has_extrabits = false;
				int extra_bits = 0;
				int num_extra_bits = i & 15;

				int bits_to_fetch = code_size;
				if (num_extra_bits) {
					int total_codesize = code_size + num_extra_bits;
					if (total_codesize <= 8) {
						has_extrabits = true;
						extra_bits = ((1 << num_extra_bits) - 1) & (code >> (8 - total_codesize));
						JPGD_ASSERT(extra_bits <= 0x7FFF);
						bits_to_fetch += num_extra_bits;
					}
				}

				if (!has_extrabits)
					pH->look_up2[code] = i | (bits_to_fetch << 8);
				else
					pH->look_up2[code] = i | 0x8000 | (extra_bits << 16) | (bits_to_fetch << 8);

				code++;
			}
		} else {
			subtree = (code >> (code_size - 8)) & 0xFF;

			currententry = pH->look_up[subtree];

			if (currententry == 0) {
				pH->look_up[subtree] = currententry = nextfreeentry;
				pH->look_up2[subtree] = currententry = nextfreeentry;

				nextfreeentry -= 2;
			}

			code <<= (16 - (code_size - 8));

			for (l = code_size; l > 9; l--) {
				if ((code & 0x8000) == 0)
					currententry--;

				if (pH->tree[-currententry - 1] == 0) {
					pH->tree[-currententry - 1] = nextfreeentry;

					currententry = nextfreeentry;

					nextfreeentry -= 2;
				} else
					currententry = pH->tree[-currententry - 1];

				code <<= 1;
			}

			if ((code & 0x8000) == 0)
				currententry--;

			pH->tree[-currententry - 1] = i;
		}

		p++;
	}
}

// Verifies the quantization tables needed for this scan are available.
void jpeg_decoder::check_quant_tables()
{
	for (int i = 0; i < m_comps_in_scan; i++)
		if (m_quant[m_comp_quant[m_comp_list[i]]] == NULL)
			stop_decoding(JPGD_UNDEFINED_QUANT_TABLE);
}

// Verifies that all the Huffman tables needed for this scan are available.
void jpeg_decoder::check_huff_tables()
{
	int i;
	for (i = 0; i < m_comps_in_scan; i++) {
		if ((m_spectral_start == 0) && (m_huff_num[m_comp_dc_tab[m_comp_list[i]]] == NULL))
			stop_decoding(JPGD_UNDEFINED_HUFF_TABLE);

		if ((m_spectral_end > 0) && (m_huff_num[m_comp_ac_tab[m_comp_list[i]]] == NULL))
			stop_decoding(JPGD_UNDEFINED_HUFF_TABLE);
	}

	for (i = 0; i < JPGD_MAX_HUFF_TABLES; i++)
		if (m_huff_num[i]) {
			if (!m_pHuff_tabs[i])
				m_pHuff_tabs[i] = (huff_tables *)alloc(sizeof(huff_tables));

			make_huff_table(i, m_pHuff_tabs[i]);
		}
}

// Determines the component order inside each MCU.
// Also calcs how many MCU's are on each row, etc.
void jpeg_decoder::calc_mcu_block_order()
{
	int component_num, component_id;
	int max_h_samp = 0, max_v_samp = 0;

	for (component_id = 0; component_id < m_comps_in_frame; component_id++) {
		if (m_comp_h_samp[component_id] > max_h_samp)
			max_h_samp = m_comp_h_samp[component_id];

		if (m_comp_v_samp[component_id] > max_v_samp)
			max_v_samp = m_comp_v_samp[component_id];
	}

	for (component_id = 0; component_id < m_comps_in_frame; component_id++) {
		m_comp_h_blocks[component_id] = ((((m_image_x_size * m_comp_h_samp[component_id]) + (max_h_samp - 1)) / max_h_samp) + 7) / 8;
		m_comp_v_blocks[component_id] = ((((m_image_y_size * m_comp_v_samp[component_id]) + (max_v_samp - 1)) / max_v_samp) + 7) / 8;
	}

	if (m_comps_in_scan == 1) {
		m_mcus_per_row = m_comp_h_blocks[m_comp_list[0]];
		m_mcus_per_col = m_comp_v_blocks[m_comp_list[0]];
	} else {
		m_mcus_per_row = (((m_image_x_size + 7) / 8) + (max_h_samp - 1)) / max_h_samp;
		m_mcus_per_col = (((m_image_y_size + 7) / 8) + (max_v_samp - 1)) / max_v_samp;
	}

	if (m_comps_in_scan == 1) {
		m_mcu_org[0] = m_comp_list[0];

		m_blocks_per_mcu = 1;
	} else {
		m_blocks_per_mcu = 0;

		for (component_num = 0; component_num < m_comps_in_scan; component_num++) {
			int num_blocks;

			component_id = m_comp_list[component_num];

			num_blocks = m_comp_h_samp[component_id] * m_comp_v_samp[component_id];

			while (num_blocks--)
				m_mcu_org[m_blocks_per_mcu++] = component_id;
		}
	}
}

// Starts a new scan.
int jpeg_decoder::init_scan()
{
	if (!locate_sos_marker())
		return JPGD_FALSE;

	calc_mcu_block_order();

	check_huff_tables();

	check_quant_tables();

	memset(m_last_dc_val, 0, m_comps_in_frame * sizeof(uint));

	m_eob_run = 0;

	if (m_restart_interval) {
		m_restarts_left = m_restart_interval;
		m_next_restart_num = 0;
	}

	fix_in_buffer();

	return JPGD_TRUE;
}

// Starts a frame. Determines if the number of components or sampling factors
// are supported.
void jpeg_decoder::init_frame()
{
	int i;

	if (m_comps_in_frame == 1) {
		if ((m_comp_h_samp[0] != 1) || (m_comp_v_samp[0] != 1))
			stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS);

		m_scan_type = JPGD_GRAYSCALE;
		m_max_blocks_per_mcu = 1;
		m_max_mcu_x_size = 8;
		m_max_mcu_y_size = 8;
	} else if (m_comps_in_frame == 3) {
		if ( ((m_comp_h_samp[1] != 1) || (m_comp_v_samp[1] != 1)) ||
		     ((m_comp_h_samp[2] != 1) || (m_comp_v_samp[2] != 1)) )
			stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS);

		if ((m_comp_h_samp[0] == 1) && (m_comp_v_samp[0] == 1)) {
			m_scan_type = JPGD_YH1V1;

			m_max_blocks_per_mcu = 3;
			m_max_mcu_x_size = 8;
			m_max_mcu_y_size = 8;
		} else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 1)) {
			m_scan_type = JPGD_YH2V1;
			m_max_blocks_per_mcu = 4;
			m_max_mcu_x_size = 16;
			m_max_mcu_y_size = 8;
		} else if ((m_comp_h_samp[0] == 1) && (m_comp_v_samp[0] == 2)) {
			m_scan_type = JPGD_YH1V2;
			m_max_blocks_per_mcu = 4;
			m_max_mcu_x_size = 8;
			m_max_mcu_y_size = 16;
		} else if ((m_comp_h_samp[0] == 2) && (m_comp_v_samp[0] == 2)) {
			m_scan_type = JPGD_YH2V2;
			m_max_blocks_per_mcu = 6;
			m_max_mcu_x_size = 16;
			m_max_mcu_y_size = 16;
		} else
			stop_decoding(JPGD_UNSUPPORTED_SAMP_FACTORS);
	} else
		stop_decoding(JPGD_UNSUPPORTED_COLORSPACE);

	m_max_mcus_per_row = (m_image_x_size + (m_max_mcu_x_size - 1)) / m_max_mcu_x_size;
	m_max_mcus_per_col = (m_image_y_size + (m_max_mcu_y_size - 1)) / m_max_mcu_y_size;

	// These values are for the *destination* pixels: after conversion.
	if (m_scan_type == JPGD_GRAYSCALE)
		m_dest_bytes_per_pixel = 1;
	else
		m_dest_bytes_per_pixel = 4;

	m_dest_bytes_per_scan_line = ((m_image_x_size + 15) & 0xFFF0) * m_dest_bytes_per_pixel;

	m_real_dest_bytes_per_scan_line = (m_image_x_size * m_dest_bytes_per_pixel);

	// Initialize two scan line buffers.
	m_pScan_line_0 = (uint8 *)alloc(m_dest_bytes_per_scan_line, true);
	if ((m_scan_type == JPGD_YH1V2) || (m_scan_type == JPGD_YH2V2))
		m_pScan_line_1 = (uint8 *)alloc(m_dest_bytes_per_scan_line, true);

	m_max_blocks_per_row = m_max_mcus_per_row * m_max_blocks_per_mcu;

	// Should never happen
	if (m_max_blocks_per_row > JPGD_MAX_BLOCKS_PER_ROW)
		stop_decoding(JPGD_ASSERTION_ERROR);

	// Allocate the coefficient buffer, enough for one MCU
	m_pMCU_coefficients = (jpgd_block_t*)alloc(m_max_blocks_per_mcu * 64 * sizeof(jpgd_block_t));

	for (i = 0; i < m_max_blocks_per_mcu; i++)
		m_mcu_block_max_zag[i] = 64;

	m_expanded_blocks_per_component = m_comp_h_samp[0] * m_comp_v_samp[0];
	m_expanded_blocks_per_mcu = m_expanded_blocks_per_component * m_comps_in_frame;
	m_expanded_blocks_per_row = m_max_mcus_per_row * m_expanded_blocks_per_mcu;
	// Freq. domain chroma upsampling is only supported for H2V2 subsampling factor (the most common one I've seen).
	m_freq_domain_chroma_upsample = false;
#if JPGD_SUPPORT_FREQ_DOMAIN_UPSAMPLING
	m_freq_domain_chroma_upsample = (m_expanded_blocks_per_mcu == 4*3);
#endif

	if (m_freq_domain_chroma_upsample)
		m_pSample_buf = (uint8 *)alloc(m_expanded_blocks_per_row * 64);
	else
		m_pSample_buf = (uint8 *)alloc(m_max_blocks_per_row * 64);

	m_total_lines_left = m_image_y_size;

	m_mcu_lines_left = 0;

	create_look_ups();
}

// The coeff_buf series of methods originally stored the coefficients
// into a "virtual" file which was located in EMS, XMS, or a disk file. A cache
// was used to make this process more efficient. Now, we can store the entire
// thing in RAM.
jpeg_decoder::coeff_buf* jpeg_decoder::coeff_buf_open(int block_num_x, int block_num_y, int block_len_x, int block_len_y)
{
	coeff_buf* cb = (coeff_buf*)alloc(sizeof(coeff_buf));

	cb->block_num_x = block_num_x;
	cb->block_num_y = block_num_y;
	cb->block_len_x = block_len_x;
	cb->block_len_y = block_len_y;
	cb->block_size = (block_len_x * block_len_y) * sizeof(jpgd_block_t);
	cb->pData = (uint8 *)alloc(cb->block_size * block_num_x * block_num_y, true);
	return cb;
}

inline jpgd_block_t *jpeg_decoder::coeff_buf_getp(coeff_buf *cb, int block_x, int block_y)
{
	JPGD_ASSERT((block_x < cb->block_num_x) && (block_y < cb->block_num_y));
	return (jpgd_block_t *)(cb->pData + block_x * cb->block_size + block_y * (cb->block_size * cb->block_num_x));
}

// The following methods decode the various types of m_blocks encountered
// in progressively encoded images.
void jpeg_decoder::decode_block_dc_first(jpeg_decoder *pD, int component_id, int block_x, int block_y)
{
	int s, r;
	jpgd_block_t *p = pD->coeff_buf_getp(pD->m_dc_coeffs[component_id], block_x, block_y);

	if ((s = pD->huff_decode(pD->m_pHuff_tabs[pD->m_comp_dc_tab[component_id]])) != 0) {
		r = pD->get_bits_no_markers(s);
		s = JPGD_HUFF_EXTEND(r, s);
	}

	pD->m_last_dc_val[component_id] = (s += pD->m_last_dc_val[component_id]);

	p[0] = static_cast<jpgd_block_t>(s << pD->m_successive_low);
}

void jpeg_decoder::decode_block_dc_refine(jpeg_decoder *pD, int component_id, int block_x, int block_y)
{
	if (pD->get_bits_no_markers(1)) {
		jpgd_block_t *p = pD->coeff_buf_getp(pD->m_dc_coeffs[component_id], block_x, block_y);

		p[0] |= (1 << pD->m_successive_low);
	}
}

void jpeg_decoder::decode_block_ac_first(jpeg_decoder *pD, int component_id, int block_x, int block_y)
{
	int k, s, r;

	if (pD->m_eob_run) {
		pD->m_eob_run--;
		return;
	}

	jpgd_block_t *p = pD->coeff_buf_getp(pD->m_ac_coeffs[component_id], block_x, block_y);

	for (k = pD->m_spectral_start; k <= pD->m_spectral_end; k++) {
		s = pD->huff_decode(pD->m_pHuff_tabs[pD->m_comp_ac_tab[component_id]]);

		r = s >> 4;
		s &= 15;

		if (s) {
			if ((k += r) > 63)
				pD->stop_decoding(JPGD_DECODE_ERROR);

			r = pD->get_bits_no_markers(s);
			s = JPGD_HUFF_EXTEND(r, s);

			p[g_ZAG[k]] = static_cast<jpgd_block_t>(s << pD->m_successive_low);
		} else {
			if (r == 15) {
				if ((k += 15) > 63)
					pD->stop_decoding(JPGD_DECODE_ERROR);
			} else {
				pD->m_eob_run = 1 << r;

				if (r)
					pD->m_eob_run += pD->get_bits_no_markers(r);

				pD->m_eob_run--;

				break;
			}
		}
	}
}

void jpeg_decoder::decode_block_ac_refine(jpeg_decoder *pD, int component_id, int block_x, int block_y)
{
	int s, k, r;
	int p1 = 1 << pD->m_successive_low;
	int m1 = (-1) << pD->m_successive_low;
	jpgd_block_t *p = pD->coeff_buf_getp(pD->m_ac_coeffs[component_id], block_x, block_y);

	JPGD_ASSERT(pD->m_spectral_end <= 63);

	k = pD->m_spectral_start;

	if (pD->m_eob_run == 0) {
		for ( ; k <= pD->m_spectral_end; k++) {
			s = pD->huff_decode(pD->m_pHuff_tabs[pD->m_comp_ac_tab[component_id]]);

			r = s >> 4;
			s &= 15;

			if (s) {
				if (s != 1)
					pD->stop_decoding(JPGD_DECODE_ERROR);

				if (pD->get_bits_no_markers(1))
					s = p1;
				else
					s = m1;
			} else {
				if (r != 15) {
					pD->m_eob_run = 1 << r;

					if (r)
						pD->m_eob_run += pD->get_bits_no_markers(r);

					break;
				}
			}

			do {
				jpgd_block_t *this_coef = p + g_ZAG[k & 63];

				if (*this_coef != 0) {
					if (pD->get_bits_no_markers(1)) {
						if ((*this_coef & p1) == 0) {
							if (*this_coef >= 0)
								*this_coef = static_cast<jpgd_block_t>(*this_coef + p1);
							else
								*this_coef = static_cast<jpgd_block_t>(*this_coef + m1);
						}
					}
				} else {
					if (--r < 0)
						break;
				}

				k++;

			} while (k <= pD->m_spectral_end);

			if ((s) && (k < 64)) {
				p[g_ZAG[k]] = static_cast<jpgd_block_t>(s);
			}
		}
	}

	if (pD->m_eob_run > 0) {
		for ( ; k <= pD->m_spectral_end; k++) {
			jpgd_block_t *this_coef = p + g_ZAG[k & 63]; // logical AND to shut up static code analysis

			if (*this_coef != 0) {
				if (pD->get_bits_no_markers(1)) {
					if ((*this_coef & p1) == 0) {
						if (*this_coef >= 0)
							*this_coef = static_cast<jpgd_block_t>(*this_coef + p1);
						else
							*this_coef = static_cast<jpgd_block_t>(*this_coef + m1);
					}
				}
			}
		}

		pD->m_eob_run--;
	}
}

// Decode a scan in a progressively encoded image.
void jpeg_decoder::decode_scan(pDecode_block_func decode_block_func)
{
	int mcu_row, mcu_col, mcu_block;
	int block_x_mcu[JPGD_MAX_COMPONENTS], m_block_y_mcu[JPGD_MAX_COMPONENTS];

	memset(m_block_y_mcu, 0, sizeof(m_block_y_mcu));

	for (mcu_col = 0; mcu_col < m_mcus_per_col; mcu_col++) {
		int component_num, component_id;

		memset(block_x_mcu, 0, sizeof(block_x_mcu));

		for (mcu_row = 0; mcu_row < m_mcus_per_row; mcu_row++) {
			int block_x_mcu_ofs = 0, block_y_mcu_ofs = 0;

			if ((m_restart_interval) && (m_restarts_left == 0))
				process_restart();

			for (mcu_block = 0; mcu_block < m_blocks_per_mcu; mcu_block++) {
				component_id = m_mcu_org[mcu_block];

				decode_block_func(this, component_id, block_x_mcu[component_id] + block_x_mcu_ofs, m_block_y_mcu[component_id] + block_y_mcu_ofs);

				if (m_comps_in_scan == 1)
					block_x_mcu[component_id]++;
				else {
					if (++block_x_mcu_ofs == m_comp_h_samp[component_id]) {
						block_x_mcu_ofs = 0;

						if (++block_y_mcu_ofs == m_comp_v_samp[component_id]) {
							block_y_mcu_ofs = 0;
							block_x_mcu[component_id] += m_comp_h_samp[component_id];
						}
					}
				}
			}

			m_restarts_left--;
		}

		if (m_comps_in_scan == 1)
			m_block_y_mcu[m_comp_list[0]]++;
		else {
			for (component_num = 0; component_num < m_comps_in_scan; component_num++) {
				component_id = m_comp_list[component_num];
				m_block_y_mcu[component_id] += m_comp_v_samp[component_id];
			}
		}
	}
}

// Decode a progressively encoded image.
void jpeg_decoder::init_progressive()
{
	int i;

	if (m_comps_in_frame == 4)
		stop_decoding(JPGD_UNSUPPORTED_COLORSPACE);

	// Allocate the coefficient buffers.
	for (i = 0; i < m_comps_in_frame; i++) {
		m_dc_coeffs[i] = coeff_buf_open(m_max_mcus_per_row * m_comp_h_samp[i], m_max_mcus_per_col * m_comp_v_samp[i], 1, 1);
		m_ac_coeffs[i] = coeff_buf_open(m_max_mcus_per_row * m_comp_h_samp[i], m_max_mcus_per_col * m_comp_v_samp[i], 8, 8);
	}

	for ( ; ; ) {
		int dc_only_scan, refinement_scan;
		pDecode_block_func decode_block_func;

		if (!init_scan())
			break;

		dc_only_scan = (m_spectral_start == 0);
		refinement_scan = (m_successive_high != 0);

		if ((m_spectral_start > m_spectral_end) || (m_spectral_end > 63))
			stop_decoding(JPGD_BAD_SOS_SPECTRAL);

		if (dc_only_scan) {
			if (m_spectral_end)
				stop_decoding(JPGD_BAD_SOS_SPECTRAL);
		} else if (m_comps_in_scan != 1) /* AC scans can only contain one component */
			stop_decoding(JPGD_BAD_SOS_SPECTRAL);

		if ((refinement_scan) && (m_successive_low != m_successive_high - 1))
			stop_decoding(JPGD_BAD_SOS_SUCCESSIVE);

		if (dc_only_scan) {
			if (refinement_scan)
				decode_block_func = decode_block_dc_refine;
			else
				decode_block_func = decode_block_dc_first;
		} else {
			if (refinement_scan)
				decode_block_func = decode_block_ac_refine;
			else
				decode_block_func = decode_block_ac_first;
		}

		decode_scan(decode_block_func);

		m_bits_left = 16;
		get_bits(16);
		get_bits(16);
	}

	m_comps_in_scan = m_comps_in_frame;

	for (i = 0; i < m_comps_in_frame; i++)
		m_comp_list[i] = i;

	calc_mcu_block_order();
}

void jpeg_decoder::init_sequential()
{
	if (!init_scan())
		stop_decoding(JPGD_UNEXPECTED_MARKER);
}

void jpeg_decoder::decode_start()
{
	init_frame();

	if (m_progressive_flag)
		init_progressive();
	else
		init_sequential();
}

void jpeg_decoder::decode_init(jpeg_decoder_stream *pStream)
{
	init(pStream);
	locate_sof_marker();
}

jpeg_decoder::jpeg_decoder(jpeg_decoder_stream *pStream)
{
	if (setjmp(m_jmp_state))
		return;
	decode_init(pStream);
}

int jpeg_decoder::begin_decoding()
{
	if (m_ready_flag)
		return JPGD_SUCCESS;

	if (m_error_code)
		return JPGD_FAILED;

	if (setjmp(m_jmp_state))
		return JPGD_FAILED;

	decode_start();

	m_ready_flag = true;

	return JPGD_SUCCESS;
}

jpeg_decoder::~jpeg_decoder()
{
	free_all_blocks();
}

jpeg_decoder_file_stream::jpeg_decoder_file_stream()
{
	m_pFile = NULL;
	m_eof_flag = false;
	m_error_flag = false;
}

void jpeg_decoder_file_stream::close()
{
	if (m_pFile) {
		fclose(m_pFile);
		m_pFile = NULL;
	}

	m_eof_flag = false;
	m_error_flag = false;
}

jpeg_decoder_file_stream::~jpeg_decoder_file_stream()
{
	close();
}

bool jpeg_decoder_file_stream::open(const char *Pfilename)
{
	close();

	m_eof_flag = false;
	m_error_flag = false;

#if defined(_MSC_VER)
	m_pFile = NULL;
	//fopen_s(&m_pFile, Pfilename, "rb");
	m_pFile = fopen(Pfilename, "rb");
#else
	m_pFile = fopen(Pfilename, "rb");
#endif
	return m_pFile != NULL;
}

int jpeg_decoder_file_stream::read(uint8 *pBuf, int max_bytes_to_read, bool *pEOF_flag)
{
	if (!m_pFile)
		return -1;

	if (m_eof_flag) {
		*pEOF_flag = true;
		return 0;
	}

	if (m_error_flag)
		return -1;

	int bytes_read = static_cast<int>(fread(pBuf, 1, max_bytes_to_read, m_pFile));
	if (bytes_read < max_bytes_to_read) {
		if (ferror(m_pFile)) {
			m_error_flag = true;
			return -1;
		}

		m_eof_flag = true;
		*pEOF_flag = true;
	}

	return bytes_read;
}

bool jpeg_decoder_mem_stream::open(const uint8 *pSrc_data, uint size)
{
	close();
	m_pSrc_data = pSrc_data;
	m_ofs = 0;
	m_size = size;
	return true;
}

int jpeg_decoder_mem_stream::read(uint8 *pBuf, int max_bytes_to_read, bool *pEOF_flag)
{
	*pEOF_flag = false;

	if (!m_pSrc_data)
		return -1;

	uint bytes_remaining = m_size - m_ofs;
	if ((uint)max_bytes_to_read > bytes_remaining) {
		max_bytes_to_read = bytes_remaining;
		*pEOF_flag = true;
	}

	memcpy(pBuf, m_pSrc_data + m_ofs, max_bytes_to_read);
	m_ofs += max_bytes_to_read;

	return max_bytes_to_read;
}

unsigned char *decompress_jpeg_image_from_stream(jpeg_decoder_stream *pStream, int *width, int *height, int *actual_comps, int req_comps)
{
	if (!actual_comps)
		return NULL;
	*actual_comps = 0;

	if ((!pStream) || (!width) || (!height) || (!req_comps))
		return NULL;

	if ((req_comps != 1) && (req_comps != 3) && (req_comps != 4))
		return NULL;

	jpeg_decoder decoder(pStream);
	if (decoder.get_error_code() != JPGD_SUCCESS)
		return NULL;

	const int image_width = decoder.get_width(), image_height = decoder.get_height();
	*width = image_width;
	*height = image_height;
	*actual_comps = decoder.get_num_components();

	if (decoder.begin_decoding() != JPGD_SUCCESS)
		return NULL;

	const int dst_bpl = image_width * req_comps;

	uint8 *pImage_data = (uint8*)jpgd_malloc(dst_bpl * image_height);
	if (!pImage_data)
		return NULL;

	for (int y = 0; y < image_height; y++) {
		const uint8* pScan_line;
		uint scan_line_len;
		if (decoder.decode((const void**)&pScan_line, &scan_line_len) != JPGD_SUCCESS) {
			jpgd_free(pImage_data);
			return NULL;
		}

		uint8 *pDst = pImage_data + y * dst_bpl;

		if (((req_comps == 1) && (decoder.get_num_components() == 1)) || ((req_comps == 4) && (decoder.get_num_components() == 3)))
			memcpy(pDst, pScan_line, dst_bpl);
		else if (decoder.get_num_components() == 1) {
			if (req_comps == 3) {
				for (int x = 0; x < image_width; x++) {
					uint8 luma = pScan_line[x];
					pDst[0] = luma;
					pDst[1] = luma;
					pDst[2] = luma;
					pDst += 3;
				}
			} else {
				for (int x = 0; x < image_width; x++) {
					uint8 luma = pScan_line[x];
					pDst[0] = luma;
					pDst[1] = luma;
					pDst[2] = luma;
					pDst[3] = 255;
					pDst += 4;
				}
			}
		} else if (decoder.get_num_components() == 3) {
			if (req_comps == 1) {
				const int YR = 19595, YG = 38470, YB = 7471;
				for (int x = 0; x < image_width; x++) {
					int r = pScan_line[x*4+0];
					int g = pScan_line[x*4+1];
					int b = pScan_line[x*4+2];
					*pDst++ = static_cast<uint8>((r * YR + g * YG + b * YB + 32768) >> 16);
				}
			} else {
				for (int x = 0; x < image_width; x++) {
					pDst[0] = pScan_line[x*4+0];
					pDst[1] = pScan_line[x*4+1];
					pDst[2] = pScan_line[x*4+2];
					pDst += 3;
				}
			}
		}
	}

	return pImage_data;
}

unsigned char *decompress_jpeg_image_from_memory(const unsigned char *pSrc_data, int src_data_size, int *width, int *height, int *actual_comps, int req_comps)
{
	jpgd::jpeg_decoder_mem_stream mem_stream(pSrc_data, src_data_size);
	return decompress_jpeg_image_from_stream(&mem_stream, width, height, actual_comps, req_comps);
}

unsigned char *decompress_jpeg_image_from_file(const char *pSrc_filename, int *width, int *height, int *actual_comps, int req_comps)
{
	jpgd::jpeg_decoder_file_stream file_stream;
	if (!file_stream.open(pSrc_filename))
		return NULL;
	return decompress_jpeg_image_from_stream(&file_stream, width, height, actual_comps, req_comps);
}

} // namespace jpgd